ANDREWS 

REINFORCED  CONCRETE 
STANDARDS 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


REINFORCED    CONCRETE 
STANDARDS 


BY 

H.  B.  AKDBEWS,  M.  AM.  Soo.  C.  E. 

II 


FIRST  EDITION 
FIRST  THOUSAND 


PUBLISHED  BY 

SIMPSON  BROS.   CORPORATION 

BOSTON 


V 

[tec, 


COPYRIGHT  1908  BY   H.   B.   ANDREWS 


PREFACE 


AMONG  the  many  publications  relating  to  reinforced  concrete,  there  seem  to  be  few 
that  answer  the  requirements  of  the  architectural  designer. 

The  majority  of  architects  are  men  who  studied  for  their  profession  before  any 
thorough  investigation  of  reinforced  concrete  construction  had  been  made.  They 
are  now  called  upon  by  their  clients  to  design  in  a  material  requiring  special  and 
intimate  study  of  its  characteristics,  and  the  solution  of  intricate  formulae  to  deter- 
mine the  proper  composition,  arrangement,  and  dimensions  of  its  component  parts. 

Many  theories  have  been  advanced  by  many  authorities  during  the  progress  of 
scientific  research  and  experiment.  Revisions  in  these  theories  have  been  made 
from  time  to  time  until  they  now  tend  to  converge  toward  a  common  focus,  but  as 
yet  these  theories  have  not  been  put  in  practical  working  shape,  and  as  a  result  many 
structures  for  which  reinforced  concrete  is  specially  adapted  are  built  of  other 
material. 

It  is  therefore  the  purpose  of  the  author  to  publish  information  of  reinforced  con- 
crete in  the  shape  of  standard  sections,  tables,  and  specifications,  that  will  enable 
designs  to  be  made  in  this  material  as  rapidly  and  as  intelligently  as  in  wood  or  steel. 

The  tables  contained  herein  have  been  in  practical  use  in  designing  and  con- 
structing several  large  buildings  in  the  City  of  Boston  and  elsewhere,  and  the  work 
designed  has  been  approved  by  conservative  concrete  specialists. 

The  need  of  a  standard  form  of  construction  with  standard  specifications  is  often 
brought  forcibly  to  mind  by  the  failure  of  reinforced  concrete  structures  through 
no  fault  of  the  materials  entering  therein,  but  through  the  lack  of  knowledge  by  the 
architect,  inspector,  or  contractor  of  the  design  or  handling  of  the  materials  which 
enter  into  the  work. 

This  work  is  divided  into  five  chapters:  — 

1.  A  Brief  Theory  of  Reinforced  Concrete  Construction,  including  original  for- 
mulae by  the  author  for  moments  of  resistance  of  T-beams  and  tables  of  standard 
sections. 

2.  Miscellaneous  Tables. 

3.  A  Reinforced  Concrete  Code. 

4.  Standard  Specifications. 

5.  Foundations. 

It  is  the  author's  purpose  to  make  this  book  as  valuable  as  possible  for  practical 
designing  and  building,  and  to  that  end  will  invite  suggestions  from  all  interested  so 
that  use  can  be  made  of  them,  if  found  practical,  for  future  editions. 

H.  B.  ANDREWS. 

BOSTON,  January,  1908. 


CHAPTER  I 

STANDARD   SECTIONS 

Design  of  Reinforced  Concrete  Beams 1 

Illustrations  of  Use  of  Diagrams  and  Tables 4 

Standard  Sections  —  Typical  Section  of  Floor 6 

Bending  Moments  —  Formulae 7 

Diagram  for  Designing  Reinforced  Concrete  Slabs 0 

Diagram  of  Bending  Moments 10 

Elements  of  Reinforced  Concrete  Beams 11 

Working  Loads  for  Reinforced  Concrete  Columns 17 

CHAPTER  II 

TABLES 

Weights  and  Areas  of  Square  and  Round  Steel  Rods.    Welded  and  Expanded  Metal     ...  18 

Proportions  of  Concrete  Aggregates 19 

Crushing  Strength  of  Portland  Cement  Concrete 20 

Material  for  100  Sq.  Ft.  Concrete  Sidewalk  or  Floor 21 

Safe  Loads  for  Wooden  Beams 22 

CHAPTER  III 

A  REINFORCED   CONCRETE   CODE 23 

CHAPTER  IV 

REINFORCED   CONCRETE  SPECIFICATIONS    ....    28 

CHAPTER  V 

FOUNDATIONS 

Loading 41 

Classes  of  Foundations • 42 

Foundations  directly  upon  the  Soil 42 

Pile  Foundations 45 


PRACTICAL  REINFORCED  CONCRETE 

STANDARDS 


CHAPTER  I 

STANDARD    SECTIONS 
DESIGN  OF  REINFORCED  CONCRETE  BEAMS 


Centroid  of 
Compression 


Neuttal  Axis 


.4    Centroid  of 
Tension 


6 

6' 

d 

- 

2 

h 
h' 


n 
a 
c 


C  — 


NOTATION 

breadth  of  web. 

6  +  4  h'  =  breadth  of  flange. 

effective  depth  of  beam. 

distance  from  top  of  beam  to  neutral  axis. 

full  depth  of  beam. 
depth  of  flange. 

—  hf  =  distance  from  lower  side  of  flange  to  neutral  axis. 

2 

distance  between  centroid  of  compression  and  neutral  axis. 

distance  between  centroid  of  compression  and  centroid  of  tension  =  Moment  arm. 

unit  compression  in  concrete  at  top  of  flange. 

unit  compression  in  concrete  at  bottom  of  flange. 

unit  stress  in  steel. 

Total  compression  in  concrete  —  89  total  stress  in  steel. 


PRACTICAL  REINFORCED   CONCRETE  STANDARDS 


FORMULAE 

The  following  assumptions  are  made  in  obtaining  formulas :  — 

I.  A  uniform  horizontal  compression  in  flange  for  a  distance  of  twice  the  depth 
of  flange  each  side  of  web.  Making  this  the  maximum  width  of  flange  tends  to  avoid 
the  danger  of  shear  along  the  web. 

II.  That  the  compression  in  the  concrete  varies  uniformly  from  the  neutral  axis 
to  the  top  of  the  flange. 

III.  That  under  working  loads,  and  until  the  steel  is  stressed  beyond  its  elastic 
limit,  the  neutral  axis  will  lie  approximately  midway  between  the  top  of  the  beam 
and  the  centre  of  tension.    This  assumption  has  been  corroborated  by  tests  made 
to  destruction  of  several  T-beams,  reinforced  with  different  percentages  of  steel, 
at  the  Massachusetts  Institute  of  Technology,  the  location  of  the  neutral  axis  being 
carefully  determined  at  each  increment  of  load. 

IV.  That  the  total  compression  in  the  concrete  will  be  balanced  by  an  equal 
tension  in  the  steel. 

V.  No  allowance  is  made  for  tensile  strength  of  concrete. 

In  Fig.  1  consider  first  a  rectangular  section  of  width  &'  and  of  depth  d,  then  the 
theoretical  compression  due  to  any  load 

~  « 

4 

This  can  be  represented  by  a  triangle 
as  shown  by  Fig.  No.  2,  where  it  is 
shown  that  the  centre  of  compression 
will  be  at  the  centre  of  gravity  of  the 
triangle  or  two  thirds  of  the  distance 

-  =  -  above  the  neutral  axis. 
2     3 

The  resistance  moment  about  the 
neutral  axis 


Vd     c 

=  —  x- 

2       2 

j 

\        ; 

^^  A   .j  _c^  _         .     \ 

\ 

c 

• 

< 

1 

I 

I 

i 

\     , 

Neutral  A*is                  \ 

FIG.  2 


cb'd     d     cb'd2 

__    vx   __  ^_ 

43        12 


(2) 


Considering  next  the  two  areas  bounded  by  m  and  2  ti,  the  theoretical  compres- 

sion  Ic'h'm 

= =  2c'/z/ra,  (3) 


and  its  moment  about  the  neutral  axis 


c'ln'm  • 


2m     4  c'hfm2 


(4) 


3  3 

The  actual  compression  in  the  T-section  equals  the  difference  between  formulas 

cb'd 


(1)  and  (3) 


-  2  c'h'm  =  0  = 


(5) 


STANDARD  SECTIONS  3 

and  the  resultant  resistance  moment  about  the  neutral  axis  equals  the  difference 

between  formulae  (2)  and  (4) 

cb'd2     4  c''h'm2  ,  . 

T"  (6) 

The  quotient  of  the  resultant  resistance  moment  divided  by  the  total  compres- 
sion is  the  resultant  moment  arm,  or 

cb'd?  _  4  c'h'm2 

12             3           cb'd2  - 16  c'h'm2 
n= = »  (7) 

cb'd     *   w          3  cb'd -24  c'h'm 
2  c'h'm 

4 
c'  =  _£!^ ;  eliminating  c'  by  substitution  in  equation  (7)  and  dividing  both  members 

..  i                                                  b'd3  -  3%  h'm3 
by  c  it  becomes  n  = (8) 

3  b'd2  -  48  h'm2 

To  determine  the  moment  of  resistance  of  a  beam  when  the  tension  in  the  steel 
is  known,  take  moments  around  the  centre  of  compression  in  the  concrete  with  a 
moment  arm  , 

a  =  -  +  n,  then  Mr  =  aS.  (9) 

2 

S  must  never  exceed  the  value  of  C  obtained  by  assuming  the  maximum  unit  stress 
c;  it  may,  however,  be  less  than  this  value,  and  the  moment  of  resistance  obtained 
by  using  the  maximum  value  of  c  will  be  decreased  in  proportion  to  the  decreased 

value  of  S. 

. 

SHEAR 

The  diagonal  tension  existing  in  the  web  of  a  concrete  beam  may  be  resolved 
into  vertical  and  horizontal  components,  each  of  which  equals  the  vertical  shear 
due  to  load  at  the  section  considered.  The  horizontal  component  will  be  taken 
care  of  by  the  horizontal  beam  rods.  The  vertical  component  will  be  taken  care 
of  by  the  concrete,  provided  it  is  not  stressed  over  60  Ibs.  per  sq.  inch  of  effective 
cross-section,1  i.  e.  the  area  included  in  the  web  between  the  centroid  of  compres- 
sion in  the  concrete  and  the  centroid  of  tension  in  the  steel,  or  distance  "a"  in 
the  tables.  If  stressed  beyond  this,  the  full  vertical  component  must  be  taken  care  of 
by  stirrups  of  steel,  in  a  horizontal  distance  equal  to  "a". 

The  stirrups  should  not  be  farther  apart  than  f  "a,"  as  with  any  wider  spacing 
they  would  lose  part  of  their  value. 

Let  V  =  total  external  vertical  shear  at  cross  section  considered, 
v=  shear  per  sq.  in.  cross-section, 

a  =  effective  depth  between  centroid  of  compression  in  concrete  and  centroid 
of  tension  in  steel ;  then 

v=  —  .  (10) 

ab 

1  This  assumption  is  made  on  the  basis  of  using  a  1-2-4  mixture  of  concrete. 


4  PRACTICAL  REINFORCED  CONCRETE  STANDARDS 

If  v  exceeds  50,  provide  stirrups  spaced  so  that  their  tensile  strength  in  a  length 
of  beam  not  exceeding  a  is  equal  to  V. 

If  beam  rods  are  trussed,  the  value  of  the  vertical  component  of  the  trussed  rods 
may  be  utilized. 

This  value  we  will  call  W. 

W=Axsx  —  .  (11) 

.31 

•  Where  A  =  sectional  area  of  steel  in  trussed  rods, 
s=  working  stress  of  steel, 
a  —  effective  depth, 
.3  I  =  horizontal  length  trussed,  portion ;  all  dimensions  being  used  as  inches. 

If  T  represents  tensile  strength  of  stirrups  in  length  of  beam  ="a,"  then 

T  =  V-W.  (12) 

To  locate  the  section  where  the  vertical  shear  is  just  60  Ibs.  per  sq.  inch,  let 
x  =  distance  of  this  section  from  point  of  support,  /=span  in  feet,  d  and  b  as 
already  used  in  previous  formulae,  and  W  the  load  per  linear  foot  of  beam  or 

girder;  then  /     30  db 

x  = (13) 

2       W 


ILLUSTRATIONS  OF  USE  OF  DIAGRAMS  AND  TABLES 

The  diagram  shown  on  page  9  is  for  use  in  obtaining  graphically  the  thickness 
and  reinforcement  of  floor  slabs.  For  illustration,  assume  a  superimposed  load  of 
125  Ibs.  per  sq.  ft.  and  a  dead  load  which  includes  the  weight  of  the  slab,  approxi- 
mated, of  75  Ibs.  per  sq.  ft.,  making  a  total  load  of  200  Ibs.  per  sq.  ft.  to  be  carried 
on  a  span  of,  say  12  feet. 

The  horizontal  lines  measure  the  span  in  feet  and  the  curved  diagonal  lines  the 
bending  moment  in  foot  pounds.  Follow  the  vertical  line  from  the  figure  12  to  the 
point  where  it  intersects  the  diagonal  line  marked  200  Ibs.  per  sq.  ft.,  and  thence 
horizontally  left  to  the  columns  marked  "Thickness  of  slab  in  inches."  The  thick- 
ness of  slab  may  be  selected  from  one  of  these  columns,  and  the  amount  of  rein- 
forcement to  be  used  with  it  is  shown  by  the  figures  in  the  column,  remembering, 
as  a  general  rule,  that  the  minimum  thickness  of  slab  and  the  maximum  amount 
of  reinforcement  is  the  most  economical.  For  the  example  given  the  thickness  of 
slab  would  be  6"  and  the  reinforcement  about  .53  sq.  inch  in  sectional  area  for 
one  foot  in  width  of  slab.  Interpolation  can  be  made  in  both  the  diagram  and  figures 
for  any  of  the  factors  entering  into  the  problem. 

The  diagram  shown  on  page  10  is  used  similarly  for  obtaining  the  bending 
moments  due  to  combined  live  and  dead  loads  for  beams.  After  the  bending  mo- 
ment due  to  the  load  is  obtained,  a  section  of  beam  whose  moment  of  resistance 
is  equal  to  this  bending  moment  may  be  selected  from  the  tables  marked  "  Elements 
of  reinforced  concrete  beams." 

For  illustration,  if  the  combined  live  and  dead  loads  on  a  beam  with  a  span  of 


STANDARD  SECTIONS  5 

20  feet  is  3000  Ibs.  per  lin.  ft.  of  beam,  then  the  bending  moment  of  150,000  foot 
Ibs.  is  obtained  at  the  left  hand  side  of  the  diagram.  Referring  to  the  tables,  it  is 
found  that  beams  £-10-26,  £-10-26,  G-10-26,  J9-10-28,  £-10-30,  £-12-24,  £- 
12-24,  G-12-24,  and  £-12-26  with  moments  of  resistance  varying  from  140,750 
to  157,609  foot  Ibs.  will  practically  fill  the  requirements.  Take,  for  example,  the 
beam  £-12-26.  The  letters  from  C  to  G  represent  thickness  of  the  slab  on  flange 
of  the  T-beam  of  from  3"  to  1".  The  letter  £,  therefore,  represents  a  thickness  of 
5".  The  first  figure,  12,  is  the  thickness  of  the  stem,  and  the  last  figure,  26,  the 
total  depth  of  beam  including  slab.  The  first  column  in  the  table  shows  the 
maximum  unit  compressive  stress  in  the  concrete;  the  second  column,  the  total 
compressive  stress  in  concrete  or  tensile  stress  in  steel ;  the  third,  the  moment 
arm  or  distance  between  centroids  of  compression  and  tension;  the  fourth,  the 
moment  of  resistance  of  beam  in  foot  pounds;  the  fifth  and  sixth,  the  size  of 
straight  and  trussed  round  rods  used  for  reinforcement;  the  seventh,  the  sec- 
tional area  of  reinforcement ;  the  eighth,  the  weight  of  reinforcement  per  lin.  ft., 
and  the  ninth,  the  sectional  area  of  concrete  under  the  slab. 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


STANDARD  SECTIONS 
BENDING  MOMENTS 

FORMULAE   FOB   BENDING   MOMENTS 

(i) 

Beam  fixed  at  one  end,  with  concentrated  load. 
B.M.=WL. 


(2) 
Beam  fixed  at  one  end,  with  uniformly  distributed  load. 

B.M.-™. 


(3) 

Beam  fixed  at  one  end,  with  combination  of  uniformly 
distributed  and  concentrated  loads. 

B.M.-PL,+^. 


(4.) 

Beam  supported  at  both  ends,  with  concentrated  load 
in  middle. 

B.M.-™. 


(5.) 

Beam  supported  at  both  ends,  with  uniformly  distri- 
buted load. 

WL 


B.M.= 


(6.) 


8 


Beam  supported  at  both  ends,  with  concentrated  load 
not  at  centre. 

n  ,,      WMN 
B.M.= 


i 

w 


•MM  4 M 

w 

L- 


PRACTICAL  REINFORCED   CONCRETE  STANDARDS 


Beam  supported  at  both  ends,  with  equal  and  sym- 
metrical concentrated  loads. 

B.  M.  = 


GRAPHICAL   METHOD   OF   DETERMINING   BENDING   MOMENTS. 

(1)  Beam  supported  at  both  ends,  with  one  concentrated  load;  to  find  the  bending 
moment  at  any  part  o/  the  beam. 

Let  W  be  the  weight  as  shown  ;  then,  as  previously  given,  the  bending  moment 

WMN 
at  W  =  ---     Plot  the  beam  and  the  location  of  W  to 


some  convenient  scale,  then  to  this,  or  some  other  scale, 
measure  the  line  WB  equal  to  the  bending  moment  already 
found.  Connect  B  with  each  end  of  the  beam.  Then  if 
we  wish  to  find  the  bending  moment  at  some  point,  as 
E,  draw  DE  vertically  to  line  CB.  Measure  DE  with  same  scale  used  in  mea- 
suring WB.  The  result  will  be  the  bending  moment  at  E. 


w  / 


I 


(2)  Beam  with  two  concentrated  loads. 

Let  W  and  P  be  the  two  concentrated  loads  as  shown.  Plot  the  bending  moments 

WB  and  PC  due  to  each  of  these  loads  by  formula 
already  given.  Complete  the  diagram  for  each  load  by 
drawing  ABD  and  ACD.  Now  the  total  bending  mo- 
ment at  W  would  be  WB,  due  to  load  W,  plus  WE,  due  to 
load  P,  or  WB  ;  and  the  total  bending  moment  at  P  would 
be  PC,  due  to  load  P,  plus  PF,  due"  to  load  W,  or  PCi. 

Draw  the  outline  ABCD,  and  this  will  represent  the  bending  moment  due  to 
both  loads,  and  will  be  the  greatest  where  the  vertical  height  scales  the  most. 

This  method  can  be  employed  to  find  the  bending  moment  due  to  any  number 
of  concentrated  loads. 


(3)  Beam  with  uniformly  distributed  load. 

At  the  middle  of  the  beam  draw  the  line  AB  = 


WL 


c 

A 

e                  \                    "5 

D 

Connect  the  points  C  B  D  by  a  parabola  and  it  will  give 
the  outline  of  the  bending  moments. 

(4)  Beam  loaded  with  both  distributed  and  concentrated  loads. 

Plot  the  outline  of  the  bending  moments  due  to  the  concentrated  loads  as  per 
Case  No.  2,  and  for  the  distributed  load  as  per  Case  No.  3.  The  vertical  distance 
between  the  upper  and  the  lower  outline  at  any  point  will  be  the  bending  moment 
at  that  point. 


STANDARD  SECTIONS 


DIAGRAM  FOR  DESIGNING  REINFORCED  CONCRETE  SLABS 
D.AI-  ^ 

"s 

x 

.; 

\ 

t^ 

Q 
00 

<Q 
ff\ 

cO 
N 

O 

X 

* 

\ 

X 

s. 

JJ 

^ 

* 

s 

X 

j[ 

X 

( 

4 

s 

x. 

N^ 

^ 

X, 

^ 

x 

v> 

K 

t 

r> 

^ 

x, 

^ 

•^ 

•"* 

\ 

^ 

"^ 

s^ 

1 

x 

\ 

™ 

^. 

^^ 

> 

x^ 

\ 

\ 

x 

•X 

X 

^ 

s 

\ 

X 

X 

c 

-^> 

^ 

X 

^•> 

^ 

\ 

^ 

X 

s 

\ 

^ 

S*»N 

1 

"x 

v^ 

s 

ss 

\ 

---* 

••»». 

"^ 

V 

x^ 

X 

x 

Jc 

^ 

J 

s 

\ 

~-«, 

~^ 

> 

*x 

j4 

X 

v 

X 

s^ 

^ 

~^. 

^ 

•^ 

—  . 

? 

^v 

x 

X 

^ 

S 

\ 

•5 

•> 

^^ 

^»> 

^ 

4 

"^ 

^ 

'x 

. 

V 

s 

L 

\ 

^*» 

L—- 

-^^ 

** 

^^. 

v 

"5 

•^ 

3> 

"X 

s 

Jj 

S 

\ 

\ 

—  ^. 

**. 

•-. 

"^^ 

^ 

•^ 

;/ 

"X 

x 

V' 

x 

X, 

x^ 

\ 

\ 

\ 

•C 

•-^ 

' 

*•••* 

•—. 

^.^ 

-  — 

•^«. 

'' 

^ 

"^, 

C 

^ 

^x 

X 

X 

s 

L^ 

\ 

\ 

\ 

=* 

S 

5? 

^> 

/r- 

^^^ 

^^ 

' 

^^ 

^», 

u< 

^ 

^ 

** 

—  ,, 

X 

s 

x 

\ 

\ 

\ 

»-. 

? 

•5 

p- 

> 

c*< 

*5 

•^ 

I 

h~« 

^ 

fc 

^ 

^ 

~»». 

"*s^ 

x 

h 

\ 

\ 

1 

N 

\ 

w1 

c 

>; 

u? 

•>, 

^ 

^, 

^ 

^ 

"^^ 

ll 

*>v 

J^ 

-x 

x 

s^ 

S 

\ 

V 

UC 

ft 

^^. 

^ 

^* 

"~^ 

X. 

•^ 

^s 

X 

x 

s 

\ 

\ 

^ 

\ 

"*^, 

•**1^^ 

•~^ 

—  . 

"^K 

'X 

"^v 

x, 

X, 

\ 

\ 

^ 

^ 

"~« 

-^ 

•s. 

^^ 

•^ 

"^v 

X 

X 

X 

s 

s 

\ 

\ 

\ 

^» 

X, 

x 

X 

x 

x 

x 

s^ 

^ 

\ 

\ 

^^N 

^x 

vv 

\, 

N 

X 

> 

s 

\ 

\ 

s 

V 

\ 

\ 

^ 

<; 

X, 

X, 

\ 

\ 

^ 

\ 

\ 

x. 

x 

X 

X 

s, 

\ 

\ 

\ 

\ 

\ 

\ 

x 

s\ 

N 

\ 

^ 

\ 

^s 

| 

S\ 

X 

n 

S 

I 

S 

\\ 

\ 

"\ 

I 

~ 

S 

\\ 

s\\ 

1 

\ 

\ 

V 

<b  £! 

3 

3 
3 

o 

o 

IO 

O 

0 

8 

00 

O 

O 
O 

00 

O 
O 

to 

0 
0 

o 

N 

O 
0 
ID 

v0 

0 

o 
o 

O 

m 

IO 

O 
O 

o 
10 

o 

0 

t^^ 
^T" 

6 

0 
0 

o 

I/O 

fO 

O 

0 
m 
rvJ 

^ 

O 

rvj 

o 
o 
in 

0 

o 
g 

o 

THICKNESS  OF  SLAB  I/N  INCHES 

2: 

> 
> 

i 
( 

) 

( 

( 

> 

3 

i 

) 

< 

V 

> 
) 

c 

u 

> 

(T> 

£ 

c 

cr 

1 

o 

CO 

< 

> 

0 

1 

) 

•) 

00 

* 

i 

% 

g 

c 

O 

in 

4 

N 

(N 

sj 

? 

f 

< 

t< 

i 
| 

v£> 

^ 

L 

) 
) 

f 

f 

<? 

10 

f 

C 

^ 

& 

§ 

0 

<fr 

f 

) 

? 

0 

"fO 

O 

$ 

0 

• 

HJ.Q./A  wi  xj  «a«,  V3*v  -ivf/oi-LDas  'jus/swaD^o^ia* 

10 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 
DIAGRAM   OF   BENDING   MOMENTS 

B.M.  =  WL2-*-8 


600,000 


55O/DOO 


5OO,OOO 


•450,000 


g    <400/>OO 

§ 

§ 

m 

H    350,000 


z 

W 


3OO.OOO 


0     250;000 


150,000 


IOO,OOO 


y 


y 


f 


.10    tl      12     13     14     15    16    17     Id    19     20    21    22    23  24-   25   26     27   28  29    3O 

SPAN  IN  FEET 


STANDARD  SECTIONS 


11 


ELEMENTS   OF   REINFORCED    CONCRETE   BEAMS 


No.  of  Beam 

c 

c=s 

a 

Mr  in 
ft.  Ibs. 

Size  of  Rods 

Sec. 
Area  of 
Steel 

Wt.  of 
Steel 
perlin.fl. 

Cu.  ft.  of 
Concrete 
under  Slab 

Bent 

Straight 

4-8 

663 

3976 

5 

1657 

One      9-16* 

.2485 

.845 

.222 

0-4-8 

401 

9621 

5 

4009 

7-8* 

.6013 

2.044 

.138 

D-4-8 

321 

9621 

5 

4009 

«        7_s» 

.6013 

2.044 

.111 

E-4-8 

267 

9621 

5 

4009 

"        7-8* 

.6013 

2.044 

.083 

4-10 

614 

4909 

6.67 

2729 

5-8* 

.3068 

1.043 

.278 

C-4-10 

422 

12566 

6.76 

7329 

tt          iff 

.7854 

2.670 

.194 

D-4-10 

314 

12566 

6.67 

6985 

tt          jff 

.7854 

2.670 

.166 

E-4-10 

262 

12566 

6.67 

6985 

tt          iff 

.7854 

2.670 

.139 

4-12 

707 

7069 

8.33 

4907 

3-4* 

.4418 

1.502 

.333 

C-4-12 

485 

15904 

8.66 

11477 

"    1  1-8" 

.9940 

3.379 

.250 

D-4-12 

334 

15904 

8.43 

11173 

"    1  1-8" 

.9940 

3.379 

.222 

E^-12 

265 

15904 

8.33 

11040 

"     1  1-8" 

.9940 

3.379 

.194 

F-4-12 

227 

15904 

8.33 

11040 

"     1  1-8* 

.9940 

3.379 

.166 

6-12 

641 

9621 

8.33 

6679 

"        7-8* 

.6013 

2.044 

.500 

C-6-12 

509 

19242 

8.57 

13742 

One  7-8* 

«        7-8" 

1.2026 

4.088 

.375 

D-6-12 

366 

19242 

8.41 

13485 

"    7-8* 

"        7-8* 

1.2026 

4.088 

.333 

E-6-12 

296 

19242 

8.33 

13357 

"    7-8" 

7-8* 

1.2026 

4.088 

.291 

F-6-12 

257 

19242 

8.33 

13357 

"    7-8" 

"        7-8* 

1.2026 

4.088 

.255 

6-14 

698 

12566 

10.00 

10472 

<t         ^ff 

it          iff 

.7854 

2.670 

.583 

C-6-14 

620 

25132 

10.40 

21781 

tt         iff 

tt          -iff 

1.5708 

5.340 

.459 

D-6-14 

433 

25132 

10.23 

21425 

tt         iff 

tt          -if 

1.5708 

5.340 

.417 

E-6-14 

333 

25132 

10.08 

21111 

ft         iff 

tt          iff 

1.5708 

5.340 

.375 

F-6-14 

280 

25132 

10.00 

20943 

tt         -10 

1* 

1.5708 

5.340 

.333 

6-16 

673 

14138 

11.67 

13749 

"    3-4* 

3-4* 

.8836 

3.005 

.667 

C-6-16 

607 

28862 

11.45 

27539 

"     7-8* 

Two     7-8* 

1.8039 

6.133 

.542 

D-6-16 

448 

28862 

11.34 

27275 

"    7-8* 

«        7-8* 

1.8039 

6.133 

.500 

E-6-16 

352 

28862 

11.10 

26697 

"    7-8" 

"        7-8* 

1.8039 

6.133 

.458 

F-6-16 

293 

28862 

11.03 

26529 

"     7-8* 

"        7-8* 

1.8039 

6.133 

.416 

6-18 

589 

14138 

13.33 

15705 

"    3-4* 

One      3-4* 

.8836 

3.005 

.750 

C-6-18 

672 

34754 

13.26 

38403 

"    7-8* 

Two       1* 

2.1721 

7.385 

.625 

D-6-18 

497 

34754 

13.19 

38200 

"     7-8* 

tt          iff 

2.1721 

7.385 

.583 

E-6-18 

386 

34754 

13.00 

37650 

"     7-8* 

1* 

2.1721 

7.385 

.541 

F-6-18 

316 

34754 

12.80 

37071 

"    7-8* 

1* 

2.1721 

7.385 

.500 

OF  THE     ^ 

UNIVERSITY 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


ELEMENTS   OF   REINFORCED    CONCRETE   BEAMS 


No.  of  Beam 

0 

a—  a 

a 

Mr  in 
ft.  Ibs. 

Size  of  Rods 

Sec. 
Area  of 
Steel 

Wt.  of 
Steel 
perlin.  ft. 

Sec.  Area 
Concrete 
under  Slab 

Bent 

Straight 

8-14 

589 

14138 

10.00 

11782 

One      3-4* 

One      3-4* 

.8836 

3.005 

.777 

C-8-14 

652 

31808 

9.66 

25605 

it           iff 

Two     7-8* 

1.9880 

6.759 

.611 

D-8-14 

547 

34753 

9.48 

27455 

"        7-8* 

«          I* 

2.1721 

7.385 

.555 

E-8-14 

447 

34753 

9.36 

27107 

"        7-8* 

a            -to 

2.1721 

7.385 

.500 

F-8-14 

388 

34753 

9.33 

27020 

7-8* 

1* 

2.1721 

7.385 

.445 

G-8-14 

345 

34753 

9.33 

27020 

7-8* 

«             Iff 

2.1721 

7.385 

.390 

8-16 

687 

19242 

11.67 

18713 

7-8* 

One      7-8* 

1.2026 

4.089 

.888 

C-8-16 

695 

37698 

11.44 

35939 

«          I// 

Two       1* 

2  .  3562 

8.011 

.722 

D-8-16 

531 

37698 

11.34 

35625 

1* 

«          I* 

2.3562 

8.011 

.667 

E-8-16 

426 

37698 

11.16 

35059 

1* 

it          10 

2.3562 

8.011 

.612 

F-8-16 

360 

37698 

11.04 

34682 

1* 

«          iff 

2.3562 

8.011 

.557 

G-8-16 

318 

37698 

11.00 

34556 

1* 

ti         jff 

2.3562 

8.011 

.500 

8-18 

697 

21207 

12.67 

22391 

3-4* 

Two     3-4* 

1  .  3254 

4.506 

1.000 

C-8-18 

636 

37698 

13.22 

41531 

«          iff 

U                    Iff 

2.3562 

8.011 

.833 

D-8-18 

616 

47712 

13.14 

52245 

"    1  1-8* 

"    1  1-8* 

2  .  9820 

10.139 

.778 

E-8-18 

490 

47712 

12.98 

51608 

"    1  1-8" 

"    1  1-8* 

2.9820 

10.139 

.722 

F-8-18 

406 

47712 

12.81 

50933 

"    1  1-8* 

"    1  1-8* 

2.9820 

10.139 

.666 

G-8-18 

351 

47712 

12.69 

50455 

"    1  1-8* 

"    1  1-8* 

2.9820 

10.139 

.610 

8-20 

691 

23759 

14.33 

28372 

"        7-8* 

3-4* 

1.4849 

5.049 

1.111 

C-8-20 

692 

44374 

14.99 

55430 

(I                  Iff 

"    1  1-8* 

2.7734 

9.430 

.944 

D-8-20 

623 

50264 

14.60 

61154 

Two       1* 

tt          iff 

3.1416 

10.681 

.888 

E-8-20 

492 

50264 

14.43 

60442 

(i          iff 

tt          iff 

3.1416 

10.681 

.833 

F-8-20 

402 

50264 

14.27 

59772 

1* 

ti          ^ff 

3.1416 

10.681 

.778 

G-8-20 

346 

50264 

14.12 

59144 

1* 

<(          iff 

3.1416 

10.681 

.722 

8-22 

685 

26311 

16.00 

35081 

7-8* 

One      3-4* 

1.6444 

5.591 

1.222 

C-8-22 

693 

47712 

16.78 

70061 

One  1  1-8* 

Twol  1-8* 

2.9820 

10.139 

1.056 

D-8-22 

662 

56940 

16.42 

77913 

Two       1* 

"    1  1-8* 

3  .  5588 

12.100 

1.000 

E-8-22 

522 

56940 

16.27 

77201 

u              -to 

"    1  1-8* 

3.5588 

12.100 

.944 

F-8-22 

425 

56940 

16.10 

76394 

«              iff 

"     1  1-8* 

3.5588 

12.100 

.888 

G-8-22 

358 

56940 

15.94 

75635 

1* 

"    1  1-8* 

3.5588 

12.100 

.833 

8-24 

681 

28863 

17.67 

42501 

One      7-8* 

(t           7    off 

I  —  o 

1.8039 

6.133 

1.333 

C-8-24 

690 

50264 

18.22 

76317 

Two       1* 

«               iff 

3.1416 

10.681 

1.167 

D-8-24 

682 

63616 

18.24 

96696 

"    1  1-8* 

"    1  1-8* 

3.9760 

13.518 

1.111 

E-8-24 

541 

63616 

18.11 

96007 

"    1  1-8* 

"    1  1-8* 

3.9760 

13.518 

1.056 

F-8-24 

442 

63616 

17.93 

95053 

"    1  1-8* 

"    1  1-8* 

3.9760 

13.518 

1.000 

G-8-24 

371 

63616 

17.75 

94099 

"    1  1-8* 

"     1  1-8* 

3.9760 

13.518 

.944 

STANDARD  SECTIONS 


13 


ELEMENTS   OF   REINFORCED    CONCRETE   BEAMS 


No.  of  Beam 

c 

C-8 

a 

Mr  in 
ft.  Ibs. 

Size  of  Rods 

Sec. 
Area  of 
Steel 

Wt.  of 
Steel 
perlin.ft. 

Sec.  Area 
Concrete 
under  Slab 

Bent 

Straight 

10-16 

676 

23759 

11.67 

23106 

One         7-8* 

Two         3-4* 

1.4849 

5.049 

1.111 

C-10-16 

620 

37698 

11.39 

35782 

tt             |ff 

«            iff 

2.3562 

8.011 

.903 

D-10-16 

661 

50264 

10.92 

45740 

Two         1" 

(t                      -to 

3.1416 

10.681 

.833 

E-10-16 

541 

50264 

10.78 

45154 

«           IP 

(I               Jff 

3.1416 

10.681 

.763 

F-10-16 

463 

50264 

10.67 

44693 

"           I" 

tt               Iff 

3.1416 

10.681 

.693 

G-10-16 

413 

50264 

10.62 

44484 

tt           I* 

tt               Jff 

3.1416 

10.681 

.623 

10-18 

658 

26311 

13.33 

29227 

One         3-4" 

Two         7-8" 

1.6444 

5.591 

1.250 

C-10-18 

663 

44374 

13.16 

48664 

1* 

1  1-8" 

2.7734 

9.430 

1.042 

D-10-18 

675 

56940 

12.91 

61258 

Two         7-8* 

Three       1* 

3.5588 

12.100 

.972 

E-10-18 

547 

56940 

12.77 

60594 

"            7-8" 

(i            -tit 

3.5588 

12.100 

.903 

F-10-18 

460 

56940 

12.62 

59882 

"            7-8" 

((            iff 

3.5588 

12.100 

.833 

G-10-18 

401 

56940 

12.52 

59407 

"            7-8" 

1* 

3.5588 

12.100 

.763 

10-20 

642 

28863 

15.00 

36079 

One         7-8* 

Two         7-8" 

1.8039 

6.133 

1.390 

C-10-20 

657 

47712 

14.91 

59282 

1  1-8* 

1  1-8* 

2.9820 

10.139 

1.181 

D-10-20 

687 

62830 

14.72 

77072 

Two         1" 

Three       1* 

3.9270 

13.352 

1.111 

E-10-20 

599 

66561 

14.50 

80379 

Three       7-8* 

tt           |ff 

4.1601 

14.144 

1.042 

F-10-20 

493 

66561 

14.33 

79486 

(t                          <-1     Off 

1  —  O 

tt            jff 

4.1601 

14.144 

.972 

G-10-20 

424 

66561 

14.18 

78653 

"           7-8" 

tt           jff 

4.1601 

14.144 

.903 

10-22 

695 

34754 

16.67 

48279 

One         7-8* 

Two         1* 

2.1721 

7.385 

1.528 

C-10-22 

698 

53995 

16.36 

73613 

Two         1" 

Three       7-8" 

3.3747 

11.474 

1.320 

D-10-22 

677 

66561 

16.66 

91159 

Three       7-8" 

1* 

4.1601 

14.144 

1.250 

E-10-22 

592 

72844 

16.56 

100525 

Two         1" 

1  1-8* 

4.5528 

15.480 

1.181 

F-10-22 

498 

72844 

16.37 

99371 

tt           I* 

"        1  1-8* 

4.5528 

15.480 

1.111 

G-10-22 

424 

72844 

16.20 

98340 

I" 

1  1-8* 

4.5528 

15.480 

1.042 

10-24 

686 

37698 

18.33 

57584 

One         1* 

Two         1* 

2.3562 

8.011 

1.667 

C-10-24 

683 

56940 

18.25 

86588 

Two         7-8" 

Three       1* 

3.5588 

12.100 

1.460 

D-10-24 

693 

66561 

18.14 

100618 

Three      7-8* 

1* 

4.1601 

14.144 

1.390 

E-10-24 

575 

79520 

18.17 

120406 

Two     1  1-8* 

1  1-8* 

4.9700 

16.898 

1.320 

F-10-24 

514 

79520 

18.01 

119346 

1  1-8* 

1  1-8* 

4.9700 

16.898 

1.250 

G-10-24 

436 

79520 

17.83 

118154 

1  1-8* 

1  1-8* 

4.9700 

16.898 

1.181 

10-26 

628 

37698 

20.00 

62830 

One          1* 

Two         1* 

2.3562 

8.011 

1.806 

C-10-26 

708 

62830 

20.00 

104717 

Two         1* 

Three       1* 

3.9270 

13.352 

1.598 

D-10-26 

659 

72844 

20.10 

122014 

t(           -j^ 

1  1-8* 

4.5528 

15.480 

1.528 

E-10-26 

663 

90686 

20.15 

152277 

1  1-8* 

1  1-4* 

5.6678 

19.270 

1.460 

F-10-26 

553 

90686 

19.93 

150614 

1  1-8* 

1  1-4* 

5.6678 

19.270 

1.390 

G-10-26 

468 

90686 

19.75 

149254 

1  1-8" 

"        1  1-4* 

5.6678 

19.  -270 

1.320 

14 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


No.  of  Beam 

c 

C-8 

a 

Mr  in 
ft.  Ibs. 

Size  of  Rods 

Sec. 
Area  of 
Steel 

Wt.  of 

Steel 
perlin.ft. 

Sec.  Area 
Concrete 
under  Slab 

Bent 

Straight 

10-28 

683 

44374 

21.67 

80132 

One           1" 

Two     1  1-8" 

2.7734 

9.430 

1.944 

C-10-28 

667 

62830 

21.74 

1  13827 

Two          1" 

Three       1" 

3.9278 

13.352 

1.736 

D-10-28 

684 

79520 

21.88 

144991 

1  1-8" 

"        1  1-8" 

4.9700 

16.898 

1.667 

E-10-28 

674 

95424 

21.72 

172717 

Three  1  1-8" 

1  1-8" 

5.9640 

20.278 

1.598 

F-10-28 

558 

95424 

21.60 

171755 

1  1-8" 

1  1-8" 

5.9640 

20.278 

1.528 

G-10-28 

471 

95424 

21.52 

171127 

1  1-8" 

1  1-8" 

5.9640 

20.278 

1.460 

10-30 

682 

47712 

23.33 

92760 

One      1  1-8" 

Two     1  1-8" 

2.9820 

10.139 

2.084 

C-10-30 

670 

66561 

23.38 

129683 

Three       1" 

Three      7-8" 

4.1601 

14.144 

1.875 

D-10-30 

653 

79520 

23.55 

156058 

Two     1  1-8" 

1  1-8" 

4.9700 

16.898 

1.806 

E-10-30 

644 

95424 

23.52 

187031 

Three  1  1-8" 

"        1  1-8" 

5.9640 

20.278 

1.736 

F-10-30 

596 

106590 

23.45 

208295 

1  1-8" 

1  1-4" 

6.6618 

22.550 

1.669 

G-10-30 

503 

106590 

23.27 

206696 

1  1-8" 

1  1-4" 

6.6618 

22.550 

1.598 

12-20 

698 

37698 

15.00 

47122 

One          1" 

Two         1" 

2.3562 

8.011 

1.667 

C-12-20 

706 

56940 

14.63 

69419 

Two         7-8" 

Three       1" 

3.5588 

12.100 

1.417 

D-12-20 

668 

66561 

14.59 

80927 

Three      7-8" 

((            j» 

4.1601 

14.144 

1.333 

E-12-20 

657 

79520 

14.47 

95888 

Two     1  1-8" 

1  1-8" 

4  .  9700 

16.898 

1.250 

F-12-20 

554 

79520 

14.31 

95328 

1  1-8" 

1  1-8" 

4.9700 

16.898 

1.167 

G-12-20 

480 

79520 

14.18 

93966 

1  1-8" 

1  1-8" 

4  .  9700 

16.898 

1.083 

12-22 

628 

37698 

16.67 

52369 

One          1" 

Two         1" 

2.3562 

8.011 

1.833 

C-12-22 

654 

56940 

16.36 

77628 

Two         7-8" 

Three       1" 

3.5588 

12.100 

1.583 

D-12-22 

679 

72844 

16.40 

99554 

«            10 

1  1-8" 

4.5528 

15.480 

1.500 

E-12-22 

696 

90686 

16.30 

123182 

"        1  1-8" 

1  1-4" 

5.6678 

19.270 

1.417 

F-12-22 

585 

90686 

16.15 

122132 

1  1-8" 

1  1-4" 

5.6678 

19.270 

1.333 

G-12-22 

503 

90686 

15.98 

120764 

1  1-8" 

1  1-4" 

5.6678 

19.270 

1.250 

12-24 

672 

44374 

18.33 

67781 

One         1" 

Two     1  1-8" 

2.7734 

9.430 

2.000 

C-12-24 

683 

62830 

18.12 

94873 

Two         1" 

Three       1" 

3.9270 

13.352 

1.750 

D-12-24 

695 

79520 

18.15 

120274 

1  1-8" 

1  1-8" 

4.9700 

16.898 

1.667 

E-12-24 

690 

95424 

18.00 

143136 

Three  1  1-8" 

"        1  1-8" 

5.9640 

20.278 

1.583 

F-12-24 

579 

95424 

17.85 

141943 

1  1-8" 

1  1-8" 

5.9640 

20.278 

1.500 

G-12-24 

496 

95424 

17.70 

140750 

1  1-8" 

1  1-8" 

5.9640 

20.278 

1.417 

12-26 

663 

47712 

20.00 

79520 

One      1-1-8" 

Two     1  1-8" 

2.9820 

10.139 

2.167 

C-12-26 

695 

69506 

19.81 

114743 

Two     1-1-8" 

Three       1" 

4.3450 

14.773 

1.918    , 

D-12-26 

654 

79520 

19.94 

132136 

1-1-8" 

1  1-8" 

4.9700 

16.898 

1.833 

E-  12-26 

651 

95424 

19.82 

157609 

Three  1-1-8" 

"        1  1-8" 

5.9640 

20.278 

1.750 

F-12-26 

611 

106590 

19.70 

174985 

1-1-8" 

1  1-4" 

6.6618 

22.650 

1.667 

G-12-26 

522 

106590 

19.52 

173386 

"        1-1-8" 

"        1  1-4" 

6.6618 

22.650 

1.583 

STANDARD  SECTIONS 


15 


ELEMENTS   OF   REINFORCED    CONCRETE   BEAMS 


No.  of  Beam 

c 

n  —  a 

a 

Mr  in 
ft.  Ibs. 

Size  of  Rods 

Sec. 
Area  of 
Steel 

Wt.  of 
Steel 
perlin.ft. 

Sec.  Area 
Concrete 
under  Slab 

\j  —  O 

Bent 

Straight 

12-28 

644 

48100 

20.75 

83173 

Two          7-8" 

Three      7-8* 

3.0065 

10.222 

2.333 

C-12-28 

685 

72844 

21.55 

130816 

«             iff 

1  1-8* 

4.5528 

15.480 

2.083 

D-12-28 

706 

90686 

21.67 

163764 

1  1-8* 

1  1-4* 

5  .  6678 

19.270 

2.000 

E-12-28 

691 

106590 

21.63 

192128 

Three  1  1-8* 

1  1-4* 

6.6618 

22.550 

1.917 

F-12-28 

641 

117756 

21.52 

211176 

1  1-4* 

1  1-4* 

7.3596 

25.023 

1.833 

G-12-28 

548 

117756 

21.38 

209802 

1  1-4* 

1  1-4* 

7.3596 

25.023 

1.750 

12-30 

703 

56940 

22.50 

106762 

Two         7-8* 

1* 

3.5588 

12.100 

2.500 

C-12-30 

705 

79520 

23.27 

154202 

1  1-8* 

1  1-8* 

4.9700 

16.898 

2.250 

D-12-30 

671 

90686 

23.45 

177216 

1  1-8* 

1  1-4* 

5.6678 

19.270 

2.167 

E-12-30 

659 

106590 

23.31 

207051 

Three  1  1-8* 

1  1-4* 

6.6618 

22.550 

2.083 

F-12-30 

613 

117756 

23.27 

228348 

1  1-4* 

«        i  i_4» 

7.3596 

25.023 

2.000 

G-12-30 

523 

117756 

23.13 

226975 

1  1-4* 

"        1  1-4* 

7.3596 

25.023 

1.917 

12-32 

654 

56940 

24.17 

1  14687 

Two         7-8* 

1* 

3.5588 

12.100 

2.667 

C-12-32 

667 

79520 

25.00 

165667 

1  1-8* 

1  1-8* 

4.9700 

16.898 

2.417 

D-12-32 

674 

95424 

25.13 

199833 

Three  1  1-8* 

1  1-8* 

5.9640 

20.278 

2.333 

E-12-32 

697 

117756 

25.18 

247091 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.250 

F-12-32 

587 

117756 

25.15 

246797 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.167 

G-12-32 

502 

117756 

25.08 

246110 

1  1-4* 

11-4* 

7.3596 

25.023 

2.083 

12-34 

689 

63830 

25.75 

136968 

Two         1* 

1* 

3.9270 

13.352 

2.833 

C-12-34 

694 

86964 

26.71 

193567 

1  1-4* 

1  1-8* 

5.4352 

18.480 

2.583 

D-12-34 

644 

95424 

26.88 

213750 

Three  1  1-8* 

1  1-8* 

5.9640 

20.278 

2.500 

E-12-34 

668 

117756 

26.98 

264755 

"        1  1-4* 

1  1-4* 

7.3596 

25.023 

2.417 

F-12-34 

565 

117756 

26.97 

264657 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.333 

G-12-34 

483 

117756 

26.86 

263577 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.250 

12-36 

673 

66561 

27.38 

124162 

Three  7-8* 

1* 

4.1601 

14.144 

3.000 

C-12-36 

690 

90686 

28.43 

214850 

Two     1  1-8* 

1  1-4* 

5.6678 

19.270 

2.750 

D-12-36 

689 

106590 

28.62 

254209 

Three  1  1-8* 

"        1  1-4* 

6.6618 

22.650 

2.667 

E-12-36 

643 

117756 

28.77 

282320 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.583 

F-12-36 

545 

117756 

28.79 

282516 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.500 

G-12-36 

466 

117756 

28.71 

281731 

1  1-4* 

1  1-4* 

7.3596 

25.023 

2.417 

15-24 

690 

56940 

18.67 

88589 

Two         1* 

Two     1  1-8* 

3.5588 

12.100 

2.500 

C-15-24 

683 

75396 

18.31 

115042 

Three       1* 

Three       1* 

4.7124 

16.022 

2.188 

D-15-24 

674 

87962 

18.16 

133116 

«            i«r 

Four        1* 

5.4978 

18.693 

2.084 

E-15-24 

649 

100528 

17.93 

150206 

Four        1* 

«           1* 

6.2832 

21.363 

1.980 

F-15-24 

631 

113880 

17.79 

168827 

it                -ttr 

1  1-8* 

7.1376 

24.268 

1.876 

G-15-24 

548 

113880 

17.67 

167888 

«                jff 

1  1-8* 

7.1376 

24^268 

1.772 

16 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


ELEMENTS   OF   REINFORCED    CONCRETE   BEAMS 


No.  of  Beam 

c 

F    ft 

a 

Mr  in 
ft.  Ibs. 

Size  of  Rods 

Sec. 
Area  of 
Steel 

Wt.  of 
Steel 
serlin.ft. 

Sec.  Area 
Concrete 
under  Slab 

Bent 

Straight 

15^27 

678 

63616 

20.83 

110427 

Two     1  1-8" 

Two     1  1-8" 

3.9960 

13.586 

2.812 

C  15-27 

671 

82072 

20.84 

143365 

"         1  1-8* 

Four        1" 

5.1296 

17.441 

2.500 

D  15-27 

662 

95424 

20.96 

166674 

Three  1  1-8" 

Three  1  1-8" 

5.9640 

20.278 

2.396 

E  15-27 

658 

111328 

20.81 

193045 

1  1-8" 

Four     1  1-8" 

6.9580 

23.657 

2.292 

F  15-27 

639 

126216 

20.62 

216881 

1  1-8" 

«        i  1-4" 

7.8884 

26.821 

2.178 

G  15-27 

573 

137382 

20.51 

234809 

"        1  1-4" 

"        1  1-4" 

8.5862 

29.193 

2.074 

15-30 

670 

67347 

22.42 

125825 

Three      7-8" 

Four        7-8" 

4.2691 

14.311 

3.124 

C  15-30 

662 

87962 

23.14 

169620 

t(                     -tO 

«            jff 

5.4978 

18.693 

2.812 

D  15-30 

649 

100528 

23.23 

194605 

Four        1" 

(t                      ]0 

6.2832 

21.363 

2.708 

E  15-30 

694 

126216 

23.35 

245595 

Three  1  1-8" 

1  1-4" 

7.8884 

26.821 

2.604 

F  15-30 

669 

142120 

23.27 

275594 

Four    1  1-8" 

1  1-4" 

8.8824 

30.200 

2.500 

G  15-30 

640 

157008 

23.15 

302895 

1  1-4" 

1  1-4" 

9.8128 

33.364 

2.396 

15-33 

670 

75396 

25.00 

157075 

Three      1" 

Three       1" 

4.7124 

16.022 

3.436 

C  15-33 

698 

100528 

25.64 

214795 

Four        1" 

Four        1" 

6.2832 

21.363 

3.124 

D  15-33 

681 

113880 

25.86 

245411 

1" 

1  1-8" 

7.1376 

24.268 

3.020 

E  15-33 

647 

126216 

25.96 

273047 

Three  1  1-8" 

1  1-4" 

7.8884 

26.821 

2.916 

F  15-33 

635 

142120 

25.90 

306742 

Four    1  1-8" 

1  1-4" 

8.8824 

30.200 

2.812 

G  15-33 

586 

157008 

25.86 

338352 

1  1-4" 

1  1-4" 

9.8128 

33.364 

2.708 

15-36 

663 

82072 

27.50 

188082 

Two     1  1-8" 

Four        1" 

5.1296 

17.441 

3.752 

C  15-36 

645 

100528 

28.18 

236073 

Four        1" 

«               -to 

6.2832 

21.363 

3.440 

D  15-36 

636 

113880 

28.45 

266657 

«            10 

1  1-8" 

7.1376 

24.268 

3.336 

E  15-36 

684 

142120 

28.60 

338719 

"        1  1-8" 

"        1  1-4" 

8.8824 

30.200 

3.228 

F  15-36 

652 

157008 

28.64 

374726 

"        1  1-4" 

1  1-4" 

9.8128 

33.364 

3.124 

G  15-36 

566 

157008 

28.59 

374072 

1  1-4" 

1  1-4" 

9.8128 

33.336 

3.020 

15-39 

652 

87962 

30.00 

219905 

Three       1" 

it               -^o 

5.4978 

18.693 

4.062 

C  15-39 

681 

113880 

30.72 

291533 

Four        1" 

"        1  1-8" 

7.1376 

24.268 

3.752 

D  15-39 

660 

126216 

31.03 

326373 

Three  1  1-8" 

"        1  1-4" 

7.8884 

26.821 

3.648 

E  15-39 

646 

142120 

31.22 

369749 

Four    1  1-8" 

1  1-4" 

8.8824 

30.200 

3.544 

F  15-39 

618 

157008 

31.34 

410053 

1  1-4" 

«        i  i_4» 

9.8128 

33.364 

3.440 

G  15-39 

538 

157008 

31.32 

409791 

"        1  1-4" 

"        1  1-4" 

9.8128 

33.364 

3.336 

15-42 

652 

95424 

32.50 

258440 

Three  1  1-8" 

Three  1  1-8" 

5.9640 

20.278 

4.375 

C  15-42 

637 

113880 

33.27 

315732 

Four        1" 

Four    1  1-8* 

7.1376 

24.268 

4.064 

D  15-42 

700 

126216 

33.62 

398173 

1  1-8" 

"        1  1-4* 

8.8824 

30.200 

3.960 

E  15-42 

675 

142120 

33.86 

443024 

"        1  1-4" 

"        1  1-4* 

9.8128 

33.364 

3.856 

F  15-42 

588r 

157008 

34.02 

445118 

"        1  1-4" 

"        1  1-4* 

9.8128 

33.364 

3.752 

G  15-42 

513 

157008 

34.04 

445379 

1  1-4" 

1  1-4* 

9.8128 

33.364 

3.648 

STANDARD  SECTIONS 


17 


WORKING   LOADS   FOR   REINFORCED    CONCRETE    COLUMNS 


500  Lbs.  per  Sq.  In. 
1-2-4  Concrete 

600  Lbs.  per  Sq.  In.  , 
l-l$-3  Concrete 

Dim.  "A" 

Square 

Round 

Octagonal 

Square 

Round 

Octagonal 

12  ins. 

Lbs. 
72000 

Lbs. 

56500 

Lbs. 

59600 

Lbs. 

86400 

Lbs. 

67900 

Lbs. 

71600 

13 

84500 

66400 

69600 

101400 

79600 

83900 

14 

98000 

77000 

81200 

117600 

92400 

97400 

15 

112500 

88400 

93100 

135000 

106000 

111800 

16 

128000 

100500 

106100 

153600 

120600 

127300 

17 

144500 

113500 

119700 

173400 

136200 

143600 

18 

162000 

127200 

134300 

194400 

152700 

161100 

19 

180500 

141800 

149500 

216600 

170100 

179400 

20 

200000 

157100 

165600 

240000 

188500 

198700 

21 

220500 

173200 

182700 

264600 

207800 

219200 

22 

242000 

190100 

200400 

2904QO 

228100 

240500 

23 

264500 

207700 

219200 

317400 

249300 

263000 

24 

288000 

226200 

238600 

345600 

271400 

286300 

25 

312500 

245400 

259000 

375000 

294500 

310800 

26 

338000 

265500 

280000 

405600 

318600 

336000 

27 

364500 

286300 

301900 

437400 

343500 

362300 

28 

392000 

307900 

324800 

470400 

369500 

389800 

29 

420500 

330300 

348300 

504600 

396300 

417900 

30 

450000 

353400 

372900 

540000 

424100 

447500 

Add  for  each  Steel  Rod 

In  1-2-4 
Cone. 

In  1-1  $-8 
Cone. 

3-4*     Dia. 

Lbs. 
1988 

Lbs. 

2386 

7-8*      " 

2485 

2982 

j»        « 

3534 

4241 

1  1-8*    " 

4473 

5368 

1  1-4*    " 

5516 

6619 

3-4*  Sq. 

2531 

3037 

7-8*    " 

3164 

3799 

jff        tt 

4500 

5400 

1  1-8*    " 

5698 

6834 

1  1-4*    " 

7031 

8437 

CHAPTER  II 


WEIGHTS   AND   AREAS   OF   SQUARE   AND   ROUND    STEEL 
RODS,    WELDED    AND    EXPANDED    METAL 


Weights  and  Areas  of  Round  and  Square  Steel  Rods 

Dia.  in 
16ths 

Area  a 
Sq.  Ins. 

Weight  a 
Lbs. 

AreaO 
Sq.  Ins. 

WeightO 
Lbs. 

0-  1 

.0039 

.013 

.0031 

.010 

2 

.0156 

.053 

.0123 

.042 

3 

.0352 

.119 

.0276 

.094 

4 

.0625 

.212 

.0491 

.167 

5 

.0977 

.333 

.0767 

.261 

6 

.1406 

.478 

.1104 

.375 

7 

.1914 

.651 

.1503 

.511 

8 

.2500 

.850 

.1963 

.667 

9 

.3164 

1.076 

.2485 

.845 

10 

.3906 

1.328 

.3068 

1.043 

11 

.4727 

1.608 

.3712 

1.262 

12 

.5625 

1.913 

.4418 

1.502 

13 

.6602 

2.245 

.5185 

1.763 

14 

.7656 

2.603 

.6013 

2.044 

15 

.8789 

2.989 

.6903 

2.347 

1-  0 

1.0000 

3.400 

.7854 

2.670 

1 

1  .  1289 

3.838 

.8866 

3.014 

2 

1.2656 

4.303 

.9940 

3.379 

3 

1.4102 

4.795 

1  .  1075 

3.766 

4 

1.5625 

5.312 

1.2272 

4.173 

5 

1.7227 

5.857 

1.3530 

4.600 

6 

1.8906 

6.428 

1.4849 

5.049 

7 

2.0664 

7.026 

1.6230 

5.518 

8 

2.2500 

7.650 

1.7671 

6.008 

Welded  Metal 

Size  Longitudinal 
Wires  W.  and  M. 
Gauge 
Sq.  Ins. 

Area  Per  Foot  in  Width 

2  in.  Centres 
Sq.  Ins. 

3  in.  Centres 
Sq.  Ins. 

4  in.  Centres 
Sq.  Ins. 

No.  0      .0738 

.4427 

.2951 

.2213 

1       .0613 

.3680 

.2453 

.1840 

2       .0541 

.3247 

.2165 

.1624 

3       .0466 

.2798 

.1866 

.1399 

4       .0399 

.2392 

.1595 

.1196 

5       .0335 

.2013 

.1342 

.1006 

6       .0289 

.1737 

.1158 

.0868 

7       .0246 

.1477 

.0984 

.0738 

8      .0206 

.1237 

.0826 

.0618 

Expanded  Metal 

Designation 

J}| 

43 

s£ 

•S^ 

*<t 

s1! 

S1 

IP 

%  "a 

CO   5 

't'S-B 

60.3 

oj  is 

fl  ^j 

V 

.2  §  -a 

S*—  2 

•« 

§B 

•2  H 

.2  **•• 

ft 

EgB 

*  d 

*  "a  ^ 

'  a 

OS 

gw 
£8 

S  ® 

CO   " 

£ 

fc| 

1-2* 

No.  18 

Stand. 

.209 

.74 

4'  or  y  X  8' 

5 

3-4" 

13 

" 

.225 

.80 

6'    X8'  or  12* 

5 

240 

1  1-2" 

12 

" 

.207 

.70 

4'   X8'  or  12' 

5 

160 

2* 

12 

" 

.166 

.56 

5'   X8'  or  12* 

5 

200 

3" 

16 

" 

.083 

.28 

6'    X8'  or  12' 

10 

480 

3* 

10 

Light 

.148 

.50 

6'   X8'  or  12* 

5 

240 

3" 

10 

Stand. 

.178 

.60 

6'   X8'  or  12' 

5 

240 

3" 

10 

Heavy 

.267 

.90 

4'    X8'  or  12' 

5 

160 

3" 

10 

Ex.  Heavy 

.356 

1.20 

6'   X8'  o    12' 

3 

144 

3" 

6 

Stand. 

.400 

1.38 

5'   X8'  o    12* 

3 

120 

3" 

6 

Heavy 

.600 

2.07 

5f   X8'  o    12* 

3 

120 

4" 

16 

Old  Style 

.093 

.42 

4i'X8'o      V 

6 

216 

6* 

4 

Stand. 

.245 

.84 

5'   X8'  o    12* 

5 

200 

6" 

4 

Heavy 

.368 

1.26 

5f   X8'  o    12' 

3 

120 

TABLES  19 

PROPORTIONS   OF    CONCRETE   AGGREGATES 


Mortars  with  No.  8  Sand 


Parts  of  sand  with  1  part  cement                                                        1  .  0 

1.5 

2.0 

2.5 

3.0 

3.5            4. 

Required  for  1  cub.  yd.  wet  mortar 

Cement  Bbls. 

4.70 
0.71 

3.70 
0.84 

3.04 
0.92 

2.58 
0.98 

2.21 
1.01 

1.94          1.72 
1.03          1.05 

Sand  cub.  yds. 

Required  for  1  cub.  yd.  dry  mortar 

Cement  Bbls. 

5.40 
0.82 

4.18 
0.95 

3.41 
1.04 

2.88 
1.10 

2.49 
1.14 

2.20          1.96 
1.17          1.20 

Sand  cub.  yds. 

Concrete 

Materials  Required  for  1  Cubic  Yard 

Proportions  of  Mixture 

With  Hazelnut  Stone 

2$-in.  Stone  and  Under 

f-in.  Stone  and  Under 

Cement 

Sand 

Stone 

Barrels 
Cement 

Cu.Yds. 

Sand 

Cu.Yds. 
Stone 

Barrels 
Cement 

Cu.  Yds. 
Sand 

Cu.Yds. 

Stone 

Barrels 
Cement 

Cu.  Yds. 
Sand 

Cu.  Yds. 
Stone 

1 

1 

2 

2.57 

0.39 

0.78 

2.63 

0.40 

0.80 

2.33 

0 

35 

0.75 

1 

1 

2.5 

2.29 

0.35 

0.87 

2.34 

0.36 

0.89 

2.10 

0 

32 

0.80 

1 

1 

3 

2.06 

0.31 

0.94 

2.10 

0.32 

0.96 

1.89 

0 

29 

0.86 

1 

1.5 

2.5 

2.05 

0.47 

0.78 

2.09 

0.48 

0.80 

1.85 

0 

42 

0.73 

1 

1.5 

3 

1.85 

0.42 

0.84 

1.90 

0.43 

0.87 

1.71 

0 

39 

0.78 

1 

1.5 

3.5 

1.72 

0.39 

0.91 

1.74 

0.40 

0.93 

1.57 

0 

36 

0.83 

1 

1.5 

4 

1.57 

0.36 

0.96 

1.61 

0.37 

0.96 

1.46 

0 

33 

0.88 

1 

2 

3.5 

1.57 

0.48 

0.83 

1.61 

0.49 

0.85 

1.44 

0 

44 

0.77 

1 

2 

4 

1.46 

0.44 

0.89 

1.48 

0.45 

0.90 

1.34 

0 

41 

0.81 

1 

2 

4.5 

1.36 

0.42 

0.93 

1.38 

0.42 

0.95 

1.26 

0 

38 

0.86 

1 

2 

5 

1.27 

0.39 

0.97 

1.29 

0.39 

0.98 

1.17 

0 

36 

0.89 

1 

2.5 

4 

1.35 

0.52 

0.82 

1.38 

0.53 

0.84 

1.24 

0 

47 

0.75 

1 

2.5 

4.5 

1.27 

0.48 

0.87 

1.29 

0.49 

0.8? 

* 

1.16 

0 

44 

0.80 

1 

2.5 

5 

1.19 

0.46 

0.91 

1.21 

0.46 

0.92 

1.10 

0 

42 

0.83 

1 

2.5 

5.5 

1.13 

0.43 

0.94 

1.15 

0.44 

0.96 

1.03 

0 

39 

0.86 

1 

2.5 

6 

1.07 

0.41 

0.97 

1.07 

0.41 

0.98 

0!98 

0 

37 

0.89 

1 

3.0 

5 

1.11 

0.51 

0.85 

1.14 

0.52 

0.87 

1.03 

0 

47 

0.78 

1 

3.0 

5.5 

1.06 

0.48 

0.89 

1.07 

0.49 

0.90 

0.97 

0 

44 

0.81 

1 

3.0 

6 

1.01 

0.46 

0.92 

1.02 

0.47 

0.93 

0.92 

0 

42 

0.84 

1 

3.0 

6.5 

0.96 

0.44 

0.95 

0.98 

0.44 

0.96 

0.88 

0 

40 

0.87 

1 

3.0 

7 

0.91 

0.42 

0.97 

0.92 

0.42 

0.98 

0.84 

0 

38 

0.89 

1 

3.5 

6 

0.95 

0.50 

0.87 

0.97 

0.51 

0.89 

0.88 

0 

46 

0.80 

1 

3.5 

6.5 

0.92 

0.49 

0.91 

0.93 

0.49 

0.92 

0.83 

0 

44 

0.82 

1 

3.5 

7 

0.87 

0.47 

0.93 

0.89 

0.47 

0.95 

0.80 

0 

43 

0.85 

1 

3.5 

7.5 

0.84 

0.45 

0.96 

0.86 

0.45 

0.98 

0'.76 

0 

41 

0.87 

1 

3.5 

8 

0.80 

0.42 

0.97 

0.83 

0.43 

1.00 

0.73 

0 

39 

0.89 

1 

4 

6 

0.90 

0.55 

0.82 

0.92 

0.56 

0.84 

0.83 

0 

51 

0.76 

1 

4 

7 

0.83 

0.51 

0.89 

0.84 

0.51 

0.90 

0.77 

0 

47 

0.80 

1 

4 

8 

0.77 

0.47 

0.93 

0.78 

0.48 

0.95 

0.71 

0 

43 

0.83 

1 

4 

9 

0.71 

0.43 

0.97 

0.72 

0.45 

1.00 

0.65 

0 

40 

0.86 

20 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


STRENGTH  OF  PORTLAND  CEMENT  CONCRETE 

AVERAGE  ACCORDING  TO  MIXTURE,  FROM  TESTS  OF  12-IN.  CUBES,  MADE  UNDER  THE  DIRECTION  OF  GEORGE  A. 
KIMBALL  CHIEF  ENGINEER,  BOSTON  ELEVATED  RAILWAY  CO.,  BY  THE  U.  S.  GOVERNMENT  AT  WATERTOWN 
ARSENAL,  MASS.,  DECEMBER,  1898,  TO  JULY,  1899 


I 


IV 


1 


S 


lu 


ULTIMATE    COMPRE55IVE    STRENGTH    IN  POUNDS    PER 


IN, 


NOTES.—  Cubes  were  crashed  at  a«:es  of  7  days  and  approximately  at  30  days,  3  months,  and  fi  months.  From  four  to  six  cubes  of  each  mixture  of  each  brand  and  age 
were  tested,  and  the  lines  in  the  diagram  are  the  average  by  mixtures  of  the  average  result  from  each  brand.  Maximum  and  minimum  individual  averages  usually  vary 
from  10  per  cent,  to  2U  per  cent,  from  the  general  average.  The  proportions  indicated,  e.  g.  1 : 0  :  2, 1 :  2  :  4,  etc.,  represent  parts  by  volume  oi  cement,  sand,  and  broken 
stone  respectively. 

Amount  of  water  used  was  just  enough  tor  concrete  to  show  moisture  on  surface  after  ramming. 

Materia.lt.—  Sand,  clean  and  sharp  ;  voids  measured  loose  33  per  cent.  Broken  stone  ;  conglomerate  from  Roxbury,  Mass.,  various  sizes,  all  passing  2  1-2  inch  ring. 
Voids  measured  loose  40.5  per  cent.  Method  of  mixing  :  cement  and  <and  turned  twice  dry,  then  moistened,  mortar  turned  on  wet  stone  and  concrete  turned  twice 
before  ramming  into  molds. 

Cubes  taken  out  of  molds  3  to  4  days  after  making,  and,  except  the  7  day  cubes,  buried  in  wet  ground  until  about  a  week  before  testing. 

Voids,  broken  corners,  or  other  defects  in  cubes  not  plastered  or  patched  in  any  way. 


TABLES 


<M 

i—  ( 

•SPA  'no  PU|BS 

CO           ^           N           O           b»           CO 

rH              C<1              CO              ^t1               ^              CO 

03 

O            O            O            O            O            O 

a 

8 

"£ 

o 

ft 

CO              »O              CO              rH              C5              CO 

1 

spweg  ^nauiao 

iO            OO            i—  I            "^            CO            M 
O              O              rH               rH              rH               C<1 

HN 

Tjl              rH              OS              CO              CO              Is— 

•i—  1 

"SPA  "nO  PaBS 

rH               <M              C^              CO              "^              »O 

<o 

09 

O           O           O           O           O           O 

o 

a 

J5 

_o 

«4H 
g 

02 

fco 

0 

1 

00            <N            CO            O            -^            <N 
CO            O            CO            I>            O            l>- 

P 

£ 

o  -    w      <H       *4       oi       €4 

'i 

3 

£ 

rH 

(N            00            TJH            O            CO            00 

•rH 

'spA  'nO  P^S 

rH                rH                C<1               CO               CO                r^ 

91 

o        o        o        o        o        o 

a 

.2 

c 

o 

ft 

»O            00            O            CO            CO            rH 

o 

E 

eiaja^g  luacago 

00               O3               t-               rH                IO               Ttl 

rH 

O              rH              rH              (N              (M              CO 

..ZSSu 

rH              rH              rH               <N 

O              CO              <N              OO              Tt<              O 
OO              O5              rH              Cfl              Tt<              CO 

5 

O               O               rH                rH                rH                1—  1 

a 
.2 

"8PA  >nO  P^S 

O              00              CO              •<*<              <N              O 

1g 

d        d        d        o        d        o 

o 

ft 

s 

PH 

Tfl               CO               (M               rH                O                Oi 

SpilBg  !}U3UI80 

O5               rH               CO               »O               t>-               00 

O              rH              rH              rH              rH              rH 

• 

CO              Ttl              O              »O              rH              CO 

<§ 

pq 

'SPA  'nO  8uois 

l>-            01            rH            (N            r^            »0 

1 

ro 

O              O              rH              rH              rH              rH 

T 

TH 

as 

OS              1>              >O              CO              O              00 

§ 

"SPA  "nO  P^^S 

CO             ^^             ^O             CO            t^*            t*1* 

1 

d        o        o        o        o        d 

0 

ft 

0 

J-l 

PH 

O               CO               »O               b-               Oi               rH 

8iaUBg^8uiao 

rH              CO              >O              !>•              Oi              (N 

rH              rH              i—  1              rH              rH               W 

eaqouj; 

(N              CO              CO              •*              ^              »O 

i 

22 


PRACTICAL   REINFORCED   CONCRETE  STANDARDS 


HARD    PINE    BEAMS    (Kidder) 

Table  of  safe  quiescent  loads  for  horizontal  rectangular  beams  of  Georgia 
yellow  pine  one  inch  broad,  supported  at  both  ends,  load  uniformly  distributed. 
For  concentrated  load  at  centre  divide  by  two.  For  permanent  loads  (such  as 
masonry)  reduce  by  10  per  cent. 

HARD-PINE    BEAMS 


Depth 
of 
Beam 

Span  in  Feet 

6 

8 

10 

12 

14 

15 

16 

18 

20 

22 

24 

25 

27 

Ins. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

6 

1,200  1     900 

720 

600 

514 

480 

7 

1,633 

1,225 

980 

816 

700 

653 

612 

8 
9 

2,133 
2,700 

1,600 

2,025 

1,280 

1,066 
1,350 

914 
1,157 

853 
1,080 

800 
1,012 

900 

1,620 

10 
12 

3,333 

4,800 

2,500 
3,600 

2,000 
2,880 

1,666 

1,428 

1,333 
1,920 

1,250 
1,800 

1,111 

1,600 

1,000 
1,440 

2,400 

2,056 

14 

6,533 

4,900 

3,920 

3,266 

2,800  |2,613  |  2,450 

2,177 

1,960 

1,782 

1,633 

1,568 

1,450 

15 

7,500 

5,633 

4,500 

3,750 

3,214 

3,000 

2,816 

2,500 

2,250 

2,045 

1,875 

1,800 

1,666 

16 

8,533 

6,400 

5,120 

4,266 

3,656 

3,412 

3,200 

2,844 

2,560 

2,327 

2,133 

2,048 

1,896 

Loads  above  and  to  the  right  of  heavy  line  will  crack  plastered  ceilings. 

SPRUCE    BEAMS    (Kidder) 

Table  of  safe  quiescent  loads  for  horizontal  rectangular  beams  one  inch  broad, 
supported  at  both  ends,  load  uniformly  distributed.  For  concentrated  load  at  centre 
divide  by  two.  For  permanent  loads  (such  as  masonry)  reduce  by  10  per  cent. 

SPRUCE    BEAMS 


Depth 
of 
Beam 

Span  in  Feet 

6 

8 

10 

12 

14 

15 

16 

17 

18 

20 

22 

24 

25 

Ins. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

6 

7 

840 
1,143 

630 

504 
686 

420 
572 

360 
490 

336 
457 

428 

857 

8 

1,493 

1,120 

896 

746 

640 

597 

560 

527 

9 

1,890 

1,417 

1,134  ]     945 

810 

756 

708 

667 

630 

10 
12 
14 

2,333 
3,360 
4,573 

1,750 
2,520 
3,430 

1,400 
2,016 
2,744 

1,166 
1,680 
2,286 

1,000 

933 
1,344 

875 
1,260 

824 
1,086 
1,614 

777 
1,120 
1,524 

700 
1,018 
1,372 

1,247 

1,143 

1,097 

1,440 
1,960 

1,828 

1,715 

15 

5,250 

3,937 

3,150 

2,625 

1,875 

2,100 

1,968 

1,853     1,750 

1,575 

1,431 

1,312 

1,260 

16 

5,973 

4,480 

3,584 

2,986 

2,540 

2,388 

2,240 

2,108 

1,991 

1,792 

1,629 

1,493 

1,433 

Loads  above  and  to  the  right  of  heavy  line  will  crack  plastered  ceilings. 


CHAPTER  III 

CODE   USED    FOR   THE    DESIGN   OF   STANDARD    REINFORCED 

CONCRETE    SECTIONS 

1.  THE  bond  between  concrete  and  steel  is  sufficient  to  make  the  two  materials 
act  as  a  homogeneous  solid  aggregate. 

2.  The  design  shall  be  based  on  the  assumption  of  the  total  live  and  dead  load 
producing  a  stress  of  16,000  pounds  per  square  inch  in  the  reinforcement,  and  a 
corresponding  stress  in  the  concrete  of  not  over  700  pounds  per  square  inch  at  the 
extreme  fibre. 

3.  The  stress  in  any  fibre  is  directly  proportional  to  the  distance  of  that  fibre 
from  the  neutral  axis. 

4.  The  modulus  of  elasticity  of  concrete  remains  constant  within  the  limits  of 
the  working  stresses. 

5.  The   dimensions   of    all   weight-bearing   members   submitted  to  transverse 
stresses  shall  be  so  proportioned  that  the  strength  of  the  metal  in  tension  shall 
determine  the  strength  of  the  member. 

6.  The  tensile  strength  of  concrete  shall  not  be  considered. 

7.  No  metal  shall  be  added  to  the  compression  side  of  a  member  to  assist  it  in 
compression. 

8.  In  the  design  of  structures  involving  reinforced  concrete  beams  and  girders 
in  connection  with  slabs,  the  beams  and  girders  shall  be  treated  as  T-sections,  with 
a  portion  of  the  slab  acting  as  a  flange.   This  portion  of  the  slab  shall  be  assumed 
to  have  a  width  equal  to  four  times  its  thickness  plus  the  width  of  the  beam. 

9.  For  all  working  loads,  the  neutral  axis  of  any  slab,  beam,  or  girder  shall  be 
assumed  midway  between  the  centroid  of  compression  of  the  steel  in  tension  and 
the  top  of  the  member. 

10.  The  ultimate  shearing  strength  of  concrete  shall  be  assumed  as  one  tenth 
its  compressive  strength. 

11.  All  reinforced  concrete  girders  acting  as  T-sections  must  be  reinforced  against 
shearing  stress  along  the  plane  of  junction  of  the  rib  and  the  flange. 

12.  Concrete  in  direct  compression  shall  be  assumed  to  have  the  following  work- 
ing values:-  1_3_6    mix>  400  Ibs.  per  sq.  in. 

1-2^-5  "  450  "  "  "  " 

1-2-4  "  500  "  "  "  " 

l_l£_3  «  600  "  "  "  " 

1-1-2  "  700  "  "  "  " 

Reinforced  concrete  columns  shall  be  designed  with  the  assumption  that  the 
stress  in  the  concrete  shall  be  simultaneous  with  ten  times  the  stress  per  square 
inch  in  the  steel. 


«4  PRACTICAL  REINFORCED  CONCRETE  STANDARDS 

13.  In  carrying  out  work  in  the  field,  special  care  must  be  taken  that  the  ribs  of 
all  girders  and  beams  shall  be  monolithic  with  the  floor  slab  for  a  distance  of  twice 
the  depth  of  slab  each  side  of  rib. 

14.  Care  must  be  taken  to  introduce  steel  enough  to  prevent  cracks  developing 
from  tensile  stresses  due  to  the  continuity  of  the  members. 

15.  In  the  determination  of  bending  moments,  beams  and  girders  shall  be  con- 
sidered as  supported  at  the  ends,  no  allowance  being  made  for  continuity  over 

Wl 

supports,  and  the  bending  moment  shall  be  figured  as  — • 

8 

16.  Floor  slabs  when  constructed  continuous,  and  when  provided  with  reinforce- 
ment at  the  top  of  slab  over  supports,  may  be  treated  as  continuous  beams,  the 

Wl 
bending  moment  being  taken  as  —  for  uniformly  distributed  loads,  or  in  case  of 

Wl 
slabs  supported  on  four  sides  and  reinforced  in  each  direction,  as  — . 

20 

17.  Where  concrete  is  exposed  to  extreme  changes  of  temperature  it  should  be 
reinforced  to  the  extent  of  .005  of  1  per  cent,  of  sectional  area  of  concrete  for  every 
degree  of  estimated  variation  of  temperature,  to  prevent  cracks  developing. 

18.  When  the  shearing  stresses  developed  in  any  part  of  a  reinforced  concrete 
structure  exceed  the  shearing  strength  of  concrete,  as  fixed,  a  sufficient  amount  of 
steel  shall  be  introduced  in  such  a  position  as  to  take  care  of  the  full  shearing  stress. 

19.  The  full  estimated  strength  of  plain  or  reinforced  concrete  columns  shall 
not  be  used  where  the  length  is  more  than  15  times  the  least  side  or  diameter. 


DISCUSSION   OF   REINFORCED    CONCRETE    CODE 

BOND.  In  order  to  develop  the  bond  between  concrete  and  steel,  all  trussed  rods 
over  columns,  or  rods  where  the  stress  is  transmitted  from  one  to  another,  shall 
have  a  lap  of  at  least  40  diameters. 

In  continuous  columns  where  the  stress  in  the  steel  is  assumed  to  be  5000  or  6000 
pounds  per  square  inch,  the  lap  may  be  15  to  18  diameters.  All  trussed  rods  ending 
at  wall  beams,  or  elsewhere,  where  the  bond  is  not  developed  by  the  length  of  the 
rod,  must  have  an  anchorage  sufficient  to  develop  their  strength.  The  best  method 
of  obtaining  this  anchorage,  where  round  rods  are  used,  is  to  thread  the  end  of  the 
rod,  and  fit  it  with  a  wrought  iron  or  steel  plate  washer  with  an  area  of  at  least 
24  times  the  sectional  area  of  the  rod,  with  two  nuts,  one  on  each  side  of  the  plate 
to  hold  it  firmly  in  place.  Tension  rods  should  be  separated  by  a  distance  of  at 
least  one  and  one  half  times  their  diameter,  and  should  be  no  nearer  the  face  of 
the  concrete. 

Steel  must  be  free  from  paint  or  oil,  and  all  rust  scales  must  be  removed  before 
imbedding  in  concrete,  as  these  will  prevent  the  proper  adhesion  of  the  concrete 
to  the  steel. 

Stirrups  used  for  shearing  stress  should  be  anchored  both  at  the  top  and  the 
bottom  of  the  beam. 


A  REINFORCED   CONCRETE  CODE  25 

STRESS  IN  STEEL  AND  CONCRETE.  The  stress  of  16,000  pounds  per  square  inch  in 
the  steel  is  that  usually  assumed  for  the  working  stress  in  structural  steel  in  build- 
ing construction,  and  there  is  no  good  reason  why  the  same  working  stress  should 
not  apply  to  concrete  reinforcement.  The  assumed  maximum  compressive  stress 
of  700  pounds  per  square  inch  in  the  concrete  is  that  obtained  by  the  straight  line 
theory,  and  is  actually  considerably  less, 

as  the  stress  strain  curve  will  follow  more I 

nearly  the  line  of  the  parabola  as  shown  in                            \N  \ 
cut.  \ 

If,  however,  the  stress  in  the  steel  pro- 
duced a  maximum  stress  of  700  pounds  NEUTRAL  AXIS 
per  square  inch  in  a  concrete  the  ultimate 
strength  of  which  is  four  times  as  much, 
then  the  first  signs  of  failure  in  a  properly 
designed  beam  would  not  result  from  com- 
pression, but  from  the  elongation  of  the 
tension  steel  and   the  consequent  cracks 
in  the  bottom  of  the  beams  resulting  therefrom,  which  begin  to  show  plainly  when 
the  steel  is  stressed  to  about  40,000  pounds  per  square  inch. 

MODULUS  OF  ELASTICITY.  The  ratio  of  the  moduli  of  elasticity  of  concrete  and 
steel  is  neglected  in  the  design  of  transverse  weight-bearing  members,  as  this  ratio 
is  always  a  variable  depending  upon  the  mixture  of  concrete  and  its  age.  It  seems 
as  reasonable  to  adopt  a  fixed  position  of  the  neutral  axis  as  to  adopt  a  fixed  ratio 
for  the  moduli  of  elasticity  upon  which  the  position  of  the  neutral  axis  would 
depend. 

Rules  3  and  4  are  therefore  correlative. 

RELATIVE  DIMENSIONS.  If  a  beam  is  so  proportioned  that  the  strength  of  the 
steel  determines  the  strength  of  the  beam,  then  ample  warning  will  be  given  before 
failure  by  overloading ;  if,  on  the  other  hand,  the  strength  of  the  beam  is  determined 
by  the  strength  of  the  concrete  in  compression,  the  beam  will  fail  without  warning, 
with  possible  disastrous  results. 

TENSILE  STRENGTH  OF  CONCRETE.  The  tensile  strength  of  concrete  is  neglected 
for  the  following  reasons :  — 

The  steel  is  undoubtedly  assisted  in  tension  by  the  concrete  until  the  elastic  limit 
of  the  concrete  is  reached,  which  will  be  when  the  steel  is  stressed  to  about  6000 
pounds  per  square  inch.  At  this  point  numerous  microscopic  cracks  will  occur  at 
the  bottom  of  the  beam,  which,  while  not  visible  and  in  no  way  affecting  the  integrity 
of  the  beam,  completely  eliminates  the  tensile  strength  of  the  concrete.  These 
cracks  will  not  become  visible  to  the  naked  eye  until  after  the  elastic  limit  of  the 
steel  is  reached. 

No  METAL  IN  COMPRESSION.  The  exact  value  of  metal  in  compression  in  a  beam 
is  an  undetermined  quantity  and  is  also  not  economical  in  design.  It  therefore 
should  be  eliminated  from  any  standard  sections,  and  in  case  it  is  necessary  to  use 
steel  in  compression  to  reduce  the  size  of  a  member,  special  consideration  should 
be  given  its  design. 


26  PRACTICAL  REINFORCED   CONCRETE  STANDARDS 

WIDTH  OF  FLANGE  OF  T-SECTIONS.  Various  assumptions  of  the  width  of  flange 
have  been  made  by  engineers.  Some  base  the  width  of  flange  upon  the  span  of 
beam,  others  upon  the  thickness  of  slab.  While  this  width  undoubtedly  depends 
more  or  less  upon  both  elements,  the  author  thinks  it  wise  to  base  it  upon  the  depth 
of  slab  for  standard  sections,  as  it  limits  the  danger  of  failure  from  longitudinal 
shear  along  the  junction  of  web  and  flange,  and  no  standard  sections  would  be 
possible  if  the  span  had  to  be  taken  into  consideration  each  time. 

LOCATION  OF  NEUTRAL  Axis.  The  location  of  neutral  axis  is  assumed  midway 
between  the  top  of  the  slab  and  the  centroid  of  tension  in  the  steel.  Tests  made  to 
destruction,  on  full-sized  beams  reinforced  with  different  percentages  of  steel  in 
which  the  position  of  the  neutral  axis  at  each  successive  increment  of  load  was  care- 
fully determined,  show  that  there  is  no  great  variation  from  this  location  until  after 
the  elastic  limit  of  the  steel  is  passed.  The  author  is  of  the  opinion  that  the  position 
of  the  neutral  axis  is  more  dependent  on  the  unit  stress  in  the  concrete  than  on  the 
unit  stress  in  the  steel. 

STRENGTH  OF  CONCRETE  IN  DIAGONAL  TENSION.  The  tensile  strength  of  con- 
crete is  usually  assumed  to  be  equal  to  about  one  tenth  its  compressive  strength. 
The  working  value  of  a  1-2-4  concrete  in  diagonal  tension,  usually  called  shear, 
may  be  assumed  to  be  60  pounds  per  square  inch. 

Referring  to  rule  11,  floor  beams  are  always  reinforced  sufficiently  against  shear 
along  the  junction  of  rib  and  flange  by  the  floor  slab  reinforcement.  This  reinforce- 
ment, however,  does  not  occur  across  girders,  and  it  is  good  conservative  practice 
to  reinforce  the  top  of  the  slab  across  girders  to  provide  against  this  shearing  action 
and  also  to  transmit  a  part  of  the  load  on  the  floor  slab  directly  to  the  girders  by 
means  of  the  cantilever  action  thus  developed.  The  slab  reinforcement  parallel 
to  the  girder  may  be  omitted  for  a  little  way  each  side  of  girder. 

STRESSES  IN  COLUMNS.  The  less  steel  in  columns,  other  than  that  needed  for 
flexure,  tends  to  economy.  After  forms  are  in  place  we  will  assume  that  a  1-1^-3 
concrete  with  a  working  value  of  600  pounds  per  square  inch  may  be  deposited 
for  eight  dollars  per  yard  or  approximately  thirty  cents  per  cubic  foot.  This  gives 
a  supporting  value  of  144  x  600  =86,400  pounds  one  foot  in  height  for  thirty  cents. 
A  sectional  area  of  14.4  square  inches  of  steel  weighing  49  pounds  and  costing  in 
place  about  one  dollar  and  a  half  per  lineal  foot  would  be  necessary  to  carry  the 
same  load. 

However,  in  high  buildings  with  heavy  loads  it  is  often  necessary  to  limit  the  size 
of  concrete  columns  by  the  introduction  of  steel.  Steel  reinforcement  may  be  used 
with  economy  up  to  5  per  cent,  of  the  sectional  area  of  the  column,  but  if  more  steel 
than  this  is  necessary,  it  is  fully  as  cheap  to  use  structural  steel  columns  based  on 
12,000  pounds  per  square  inch  and  fireproof  them. 

A  1-1 J-3  concrete  should  be  used  in  columns  with  a  1-2-4  mix  in  the  floor  slab, 
as  the  confined  1-2-4  concrete  in  the  floor  slab  through  which  the  column  passes 
has  quite  as  much  value  as  the  1-1 J-3  concrete  midway  between  floors. 

Hooped  columns  based  on  Considere's  theory  have  been  designed  with  as  high 
a  working  stress  as  1000  pounds  per  square  inch,  but  in  the  light  of  experiments 
made  at  the  Watertown  Arsenal  by  United  States  Army  engineers,  such  a  working 


A  REINFORCED   CONCRETE   CODE  27 

stress  does  not  seem  rational,  and  the  author  would  not  advise  the  use  of  excessive 
values  in  compression  until  further  investigation  sufficiently  warrants  it. 

There  is  also  an  element  of  danger  involved  in  carrying  so  high  a  compression 
value  through  the  intersecting  floor  beams  and  girders  with  their  many  reinfor- 
cing rods  around  which  it  is  necessary  to  use  extreme  care  in  the  placing  and  tamp- 
ing of  concrete. 

CONTINUITY  OF  MEMBERS.  In  monolithic  structures  stresses  are  developed  over 
all  supports  by  the  negative  bending  moments  which  must  be  taken  care  of  by  a 
sufficient  quantity  of  steel  to  prevent  cracks  developing.  In  beams  and  girders,  if 
one  half  the  number  of  tension  rods  are  trussed  over  the  supports  and  lapped  for 
a  sufficient  distance  to  develop  their  strength,  all  necessary  provision  is  made  against 
cracking  of  concrete  over  supports.  All  concrete  liable  to  be  affected  by  extreme 
temperature  changes  should  be  reinforced  with  steel  to  prevent  cracks  developing. 

In  the  case  of  floor  slabs,  the  floor  reinforcement  should  be  kept  down  to  within 
one  inch  of  the  bottom  of  the  slab  midway  between  beams  and  lifted  to  within  one 
inch  of  the  top  of  the  slab  over  the  beams. 

BENDING  MOMENTS.  In  continuous  beams,  the  maximum  bending  moment  when 
adjacent  spaces  are  loaded  occurs  over  the  supports.  T-beam  sections  are  designed 
for  the  maximum  amount  of  steel  at  the  bottom  of  the  beam,  midway  between  sup- 
ports, this  steel  being  balanced  in  compression  by  the  T-section  of  concrete.  The 

Wl 
amount  of  steel  thus  obtained  by  using  the  formula  —  is  sufficient  to  relieve  the 

stress  over  the  columns  and  provide  for  any  unequal  loading  of  bays,  the  internal 
stresses  adjusting  themselves  to  the  varied  position  of  load. 

Wl 

Some  building  ordinances  allow  the  bending  moment  to  be  assumed  —  with  a 

10 

maximum  amount  of  steel  over  the  columns.  This  is  liable  to  cause  a  weakness 
in  compression  at  the  bottom  of  the  beam  next  to  the  column  before  the  strength 
of  the  steel  is  developed,  unless  the  area  of  concrete  at  the  bottom  of  the  beam  is 
increased  by  haunching  the  beam. 

Wl 

The  formula  —  may  be  used  for  floor  slabs  when  the  reinforcement  is  lifted  over 
10 

the  beams. 


CHAPTER  IV 

REINFORCED    CONCRETE    SPECIFICATIONS 

* 

CEMENT.  The  cement  is  to  be  stored  in  a  suitable  building  and  kept  free  from 
moisture  before  using.  It  is  to  be  so  placed  as  to  admit  identification  and  inspection 
of  each  shipment  and  so  that  the  lots  arriving  first  shall  be  used  first.  Cement  shall 
be  furnished  at  such  periods  that  a  seven-day  test  can  be  made  on  each  lot  before 
it  is  necessary  for  use.  All  cement  shall  be  of  a  high  grade  American  Portland,  and 
shall  comply  with  the  specifications  adopted  by  the  American  Society  for  Testing 
Materials.  The  cement  tests  shall  be  made  as  specified  by  persons  skilled  in  this 
work,  at  the  expense  of  the  owner. 

All  necessary  assistance  shall  be  provided  the  representative  of  the  owner  in 
obtaining  such  samples  as  he  requires. 

SAND.  The  sand  must  be  clean,  sharp,  and  free  from  loam,  clay,  mica,  or  other 
objectionable  material.  Samples  of  the  sand  used  shall  be  furnished  the  cement 
tester  from  time  to  time  as  required  by  the  architect,  so  that  the  strength  of  a  1-3 
mortar  can  be  observed. 

CRUSHED  STONE  OB  GRAVEL.  The  crushed  stone  or  gravel  must  be  clean,  hard, 
and  free  from  foreign  matter.  Crushed  slate,  shale,  or  limestone  shall  not  be  used 
in  reinforced  concrete  construction. 

Dust  shall  be  screened  out  of  crushed  stone.  Sand  shall  be  screened  out  of  gravel, 
but  may  be  remixed  with  it  in  the  proper  proportions,  if  of  the  specified  quality. 

For  heavy  foundations,  stone  which  has  passed  through  a  4 -in.  mesh  may  be 
used.  For  smaller  footings  and  thick  walls,  stone  which  has  passed  through  a 
3-in.  mesh  may  be  used.  For  reinforced  columns,  girders,  beams,  slabs,  and  thin 
walls  all  stones  shall  pass  through  a  1-in.  mesh. 

MIXING.  Proper  boxes  or  gauges  must  be  provided  for  measuring  sand  and 
stone.  95  pounds  of  cement,  or  one  bag,  shall  be  assumed  as  .95  cubic  feet. 

Concrete  shall  be  mixed  in  an  approved  mixing  machine,  unless  permission  is 
obtained  from  the  architect  to  mix  by  hand. 

In  either  case  all  concrete  shall  be  mixed  to  his  entire  satisfaction,  and  no  con- 
crete shall  be  placed  in  the  work  until  each  particle  of  stone  is  thoroughly  covered 
with  mortar. 

Sufficient  water  is  to  be  used  to  produce  a  "  wet  "  mix,  but  not  enough  so  that 
the  concrete  will  be  sloppy  in  the  wheelbarrows  with  water  standing  at  the  top 
before  depositing. 

Concrete  is  to  be  mixed  in  the  following  proportions:  For  the  lower  part  of 
footings  and  for  foundation  walls,  one  part  cement,  two  and  one  half  parts  sand, 
and  five  parts  broken  stone  or  gravel.  For  the  upper  part  of  footings  and  for 
columns,  one  part  cement,  one  and  one  half  parts  sand,  and  three  parts  broken 


REINFORCED   CONCRETE  SPECIFICATIONS  29 

stone.  For  all  other  reinforced  work,  one  part  cement,  two  parts  sand,  and  four 
parts  broken  stone.  Any  variation  from  these  materials  or  proportions  must  be  with 
the  written  permission  of  the  architect. 

PLACING  CONCRETE.  Concrete  shall  be  deposited  wet  enough  so  that  it  will 
require  but  little  tamping,  but  care  must  be  taken  in  spading  next  to  the  forms  to 
press  back  the  stone  and  bring  the  mortar  to  the  surface,  so  as  to  insure  a  smooth 
finish.  Spading  will  also  be  necessary  to  bring  the  air  bubbles  to  the  surface,  espe- 
cially in  deep  columns.  Columns  for  each  floor  shall  be  filled  to  the  height  of  the 
bottom  of  the  deepest  intersecting  beam  or  girder  in  two  or  more  operations.  After 
columns  are  filled  sufficient  time  shall  elapse  before  work  is  continued  on  the  floor 
to  allow  shrinkage  of  concrete  in  columns  to  take  place.  The  beams,  girders,  and 
floor  slabs  are  to  be  laid  as  a  monolith,  and  on  no  account  shall  work  be  stopped 
except  on  such  lines  as  are  previously  determined  or  as  directed  at  the  time  by  the 
architect.  As  a  general  rule,  working  joints  shall  be  through  the  middle  of  the  bay. 
Joints  where  work  is  stopped  are  to  be  cleaned  with  a  wire  brush,  and  painted  with 
a  neat  cement  grout  before  any  concrete  is  laid  against  them  on  resuming  work. 

GRANOLITHIC  SURFACES.  Where  granolithic  surfaces  are  specified,  the  upper 
inch  is  to  be  composed  of  one  part  cement,  three  fourths  part  clean,  sharp,  coarse 
sand,  and  three  fourths  part  crushed  stone  through  a  half -inch  mesh  with  the  dust 
screened  out. 

It  is  preferable  that  this  surface  be  laid  monolithic  with  the  floor  slab,  and  if  so 
it  shall  be  part  of  the  effective  depth  of  the  floor  slab.  If  it  is  impracticable  to  lay 
the  granolithic  surface  at  the  same  time  as  the  floor  slab,  then  the  total  thickness 
of  floor  shall  be  increased  one  inch,  and  the  granolithic  surface  shall  be  bonded  to 
the  base  in  an  approved  manner.  The  contractor  must  guarantee  that  the  grano- 
lithic top  shall  not  separate  from  the  base  for  a  period  of  one  year  from  completion 
of  work. 

FORMS.  Forms  shall  be  constructed  in  a  thorough  and  substantial  manner  and 
shall  be  well  braced  to  prevent  any  distortion.  All  lumber  adjacent  to  concrete  shall 
be  planed  to  uniform  thickness,  shall  be  laid  with  tight  joints  to  prevent  cement  from 
escaping,  and  shall  be  free  from  shakes  and  loose  knots.  All  floor  boarding  shall  be 
laid  in  narrow  widths  of  6  inches  or  less,  and  special  care  must  be  taken  to  prevent 
uneven  surfaces.  Chamfer  all  corners  of  beams,  girders,  and  columns  by  nailing 
triangular  strips  to  the  forms.  A  trap  door  shall  be  left  at  the  bottom  of  each  column 
form  to  admit  cleaning  out  dirt  before  concrete  is  deposited.  No  forms  shall  be 
removed  until  the  concrete  is  thoroughly  set,  and  has  obtained  sufficient  strength 
to  prevent  any  distortion  or  deflection.  After  the  forms  are  removed  the  contractor 
is  to  repair  any  defective  work  upon  instruction  by  the  architect,  and  if  in  his  opin- 
ion such  defects  are  sufficient  to  cause  undue  weakness,  the  whole  of  the  member 
affected  must  be  removed  and  replaced.  After  the  forms  are  removed,  cut  off  all 
fins,  patch  up  defects,  and  correct  other  irregularities. 

REINFORCEMENT.  The  steel  used  for  reinforcement  shall  consist  of  such  shapes 
and  sizes  as  are  shown  on  the  plans  or  approved  by  the  architect.  It  shall  conform 
to  the  "Manufacturers'  Standard  Specifications"  for  "  Medium  "  steel.  Under 
these  specifications  it  may  be  either  Bessemer  or  Open  Hearth,  although  Open 


30  PRACTICAL  REINFORCED  CONCRETE  STANDARDS 

Hearth  shauld  be  given  the  preference.  It  shall  have  an  ultimate  strength  of  60,- 
000  to  70,000  pounds  per  square  inch.  It  shall  have  an  elastic  limit  of  not  less  than 
half  its  ultimate  strength.  The  percentage  of  elongation  shall  be  1, 400,000  -s-  ulti- 
mate strength.  It  shall  bend  180  degrees  to  a  diameter  equal  to  thickness  of  piece 
tested,  without  fracture  on  outside  of  bent  portion. 

No  steel  used  in  reinforcing  concrete  shall  be  painted  or  coated  with  any  oily 
material,  but  shall  be  clean  and  free  from  rust  scales. 

Before  placing,  all  steel  shall  be  bent  true  to  templates  as  required  on  the  draw- 
ings. Care  shall  be  taken  in  handling  to  preserve  the  shape  of  each  piece,  and  in 
setting  to  place  each  piece  or  group  of  pieces  in  their  proper  locations. 

All  steel  reinforcement  for  columns,  beams,  and  girders  shall  be  assembled  before 
being  placed  in  the  forms,  in  such  a  manner  as  to  hold  all  component  parts  rigidly 
in  their  proper  locations  and  to  prevent  any  change  in  location  of  steel  during  the 
placing,  tamping,  or  spading  of  the  concrete.  Rods  shall  be  lapped  40  diameters 
over  supports  and  dead  ends  shall  be  threaded  and  provided  with  two  standard 
nuts  inclosing  a  5-8  inch  steel  washer  with  an  area  of  twenty-four  times  the  sec- 
tional area  of  the  rod  or  rods  which  it  engages. 

PROTECTION  AGAINST  ELEMENTS.  In  hot  weather  concrete  shall  be  kept  wet  one 
week  after  placing,  and  if  possible  covered  from  the  sun's  rays. 

Stone  intended  for  use  in  concrete  that  has  long  been  exposed  to  the  sun  shall 
be  thoroughly  wet  down  before  using. 

Concrete  shall  be  absolutely  protected  from  freezing.  Any  concrete  which  has 
been  allowed  to  freeze  within  forty-eight  hours  from  the  time  of  depositing  shall 
be  removed  immediately  and  replaced  with  new  concrete. 


AMERICAN   SOCIETY   FOR   TESTING   MATERIALS 

REPORT    OF    COMMITTEE    ON    STANDARD    SPECIFICATIONS    FOR    PORTLAND    CEMENT 

Adopted  June  17, 1904 

GENERAL  OBSERVATIONS 

1.  These  remarks  have  been  prepared  with  a  view  of  pointing  out  the  pertinent 
features  of  the  various  requirements  and  the  precautions  to  be  observed  in  the  inter- 
pretation of  the  results  of  the  tests. 

2.  The  committee  would  suggest  that  the  acceptance  or  rejection  under  these 
specifications  be  based  on  tests  made  by  an  experienced  person  having  the  proper 
means  for  making  the  tests. 

SPECIFIC   GRAVITY 

3.  Specific  gravity  is  useful  in  detecting  adulteration  or  underburning.    The 
results  of  tests  of  specific  gravity  are  not  necessarily  conclusive  as  an  indication  of 
the  quality  of  a  cement,  but  when  in  combination  with  the  results  of  other  tests 
may  afford  valuable  indications. 


REINFORCED  CONCRETE  SPECIFICATIONS  31 

FINENESS 

4.  The  sieves  should  be  kept  thoroughly  dry. 

TIME   OF   SETTING 

5.  Great  care  should  be  exercised  to  maintain  the  test  pieces  under  as  uniform 
conditions  as  possible.    A  sudden  change  or  wide  range  of  temperature  in  the  room 
in  which  the  tests  are  made,  a  very  dry  or  humid  atmosphere,  and  other  irregular- 
ities, vitally  affect  the  rate  of  setting. 

TENSILE   STRENGTH 

6.  Each  consumer  must  fix  the  minimum  requirements  for  tensile  strength  to 
suit  his  own  conditions.   They  shall,  however,  be  within  the  limits  stated. 

CONSTANCY   OF   VOLUME 

7.  The  tests  for  constancy  of  volume  are  divided  into  two  classes,  the  first  normal, 
the  second  accelerated.  The  latter  should  be  regarded  as  a  precautionary  test  only, 
and  not  infallible.    So  many  conditions  enter  into  the  making  and  interpreting  of 
it  that  it  should  be  used  with  extreme  care. 

8.  In  making  the  pats  the  greatest  care  should  be  exercised  to  avoid  initial  strains 
due  to  molding  or  to  too  rapid  drying-out  during  the  first  twenty-four  hours.   The 
pats  should  be  preserved  under  the  most  uniform  conditions  possible,  and  rapid 
changes  of  temperature  should  be  avoided. 

9.  The  failure  to  meet  the  requirements  of  the  accelerated  tests  need  not  be  suf- 
ficient cause  for  rejection.  The  cement  may,  however,  be  held  for  twenty-eight  days, 
and  a  re-test  made  at  the  end  of  that  period.   Failure  to  meet  the  requirements  at 
this  time  should  be  considered  sufficient  cause  for  rejection,  although  in  the  present 
state  of  our  knowledge  it  cannot  be  said  that  such  failure  necessarily  indicates 
unsoundness,  nor  can  the  cement  be  considered  entirely  satisfactory  simply  be- 
cause it  passes  the  tests. 


STANDARD   SPECIFICATIONS  FOR   PORTLAND   CEMENT 
GENERAL  CONDITIONS 

1.  All  cement  shall  be  inspected. 

2.  Cement  may  be  inspected  either  at  the  place  of  manufacture  or  on  the  work. 

3.  In  order  to  allow  ample  time  for  inspecting  and  testing,  the  cement  should  be 
stored  in  a  suitable  weather-tight  building  having  the  floor  properly  blocked  or 
raised  from  the  ground. 

4.  The  cement  shall  be  stored  in  such  a  manner  as  to  permit  easy  access  for 
proper  inspection  and  identification  of  each  shipment. 

5.  Every  facility  shall  be  provided  by  the  contractor,  and  a  period  of  at  least 
twelve  days  allowed  for  the  inspection  and  necessary  tests. 


32  PRACTICAL   REINFORCED   CONCRETE  STANDARDS 

6.  Cement  shall  be  delivered  in  suitable  packages  with  the  brand  and  name  of 
manufacturer  plainly  marked  thereon. 

7.  A  bag  of  cement  shall  contain  94  pounds  of  cement  net.  Each  barrel  of  Port- 
land cement  shall  contain  4  bags,  and  each  barrel  of  natural  cement  shall  contain 
3  bags  of  the  above  net  weight. 

8.  Cement  failing  to  meet  the  seven-day  requirements  may  be  held  awaiting  the 
results  of  the  twenty-eight- day  tests  before  rejection. 

9.  All  tests  shall  be  made  in  accordance  with  the  methods  proposed  by  the  Com- 
mittee on  Uniform  Tests  of  Cement  of  the  American  Society  of  Civil  Engineers 
presented  to  the  Society  January  21,  1903,  and  amended  January  20,  1904,  with 
all  subsequent  amendments  thereto.     (See  addendum  to  these  specifications.) 

10.  The  acceptance  or  rejection  shall  be  based  on  the  following  requirements : 

PORTLAND  CEMENT 

11.  Definition.    This  term  is  applied  to  the  finely  pulverized  product  resulting 
from  the  calcination  to  incipient  fusion  of  an  intimate  mixture  of  properly  propor- 
tioned argillaceous  and  calcareous  materials,  and  to  which  no  addition  greater  than 
3  per  cent,  has  been  made  subsequent  to  calcination. 

SPECIFIC   GRAVITY 

12.  The  specific  gravity  of  the  cement,  thoroughly  dried  at  100°  C.,  shall  be  not 
less  than  3.10. 

FINENESS 

13.  It  shall  leave  by  weight  a  residue  of  not  more  than  8  per  cent,  on  the  No. 
100,  and  not  more  than  25  per  cent,  on  the  No.  200  sieve. 

TIME   OF   SETTING 

14.  It  shall  develop  initial  set  in  not  less  than  thirty  minutes,  but  must  develop 
hard  set  in  not  less  than  one  hour,  nor  more  than  ten  hours. 

TENSILE    STRENGTH 

15.  The  minimum  requirements  for  tensile  strength  for  briquettes  one  inch  square 
in  section  shall  be  within  the  following  limits,  and  shall  show  no  retrogression  in 
strength  within  the  periods  specified.1 

AGE  NEAT  CEMENT  STRENGTH 

24  hours  in  moist  air 150-200  Ibs. 

7  days  (1  day  in  moist  air,  6  days  in  water) 450-550 

28  days  (1  day  in  moist  air,  27  days  in  water) 550-650 

ONE  PART  CEMENT,  THREE  PARTS  SAND 

7  days  (1  day  in  moist  air,  6  days  in  water) 150-200 

28  days  (1  day  in  moist  air,  27  days  in  water) 200-300 

1  For  example  the  minimum  requirements  for  the  twenty-four  hour  neat  cement  test  should  be  some  value 
within  the  limits  of  150  and  200  pounds,  and  so  on  for  each  period  stated. 


REINFORCED  CONCRETE  SPECIFICATIONS  33 

CONSTANCY   OF  VOLUME 

16.  Pats  of  neat  cement  about  three  inches  in  diameter,  one  half  inch  thick  at 
the  centre,  and  tapering  to  a  thin  edge,  shall  be  kept  in  moist  air  for  a  period  of 
twenty-four  hours. 

(a)  A  pat  is  then  kept  in  air  at  normal  temperature  and  observed  at  intervals 
for  at  least  twenty-eight  days. 

(b)  Another  pat  is  kept  in  water  maintained  as  near  70°  F.  as  practicable,  and 
observed  at  intervals  for  at  least  twenty -eight  days. 

(c)  A  third  pat  is  exposed  in  any  convenient  way  in  an  atmosphere  of  steam, 
above  boiling  water,  in  a  loosely  closed  vessel  for  five  hours. 

17.  These  pats,  to  satisfactorily  pass  the  requirements,  shall  remain  firm  and 
hard  and  show  no  signs  of  distortion,  checking,  cracking,  or  disintegrating. 

SULPHURIC   ACID   AND   MAGNESIA 

18.  The  cement  shall  not  contain  more  than  1.75  per  cent,  of  anhydrous  sul- 
phuric acid  (SO3),  nor  more  than  4  per  cent,  of  magnesia  (MgO). 

Submitted  on  behalf  of  the  committee. 

GEORGE  F.  SWAIN,  Chairman. 
GEORGE  S.  WEBSTER,  Vice-Chairman. 
RICHARD  L.  HUMPHREY,  Secretary. 

ADDENDUM 


SAMPLING 

1.  Selection  of  Sample.     The  sample  shall  be  a  fair  average  of  the  contents  of 
the  package ;  it  is  recommended  that,  where  conditions  permit,  one  barrel  in  every 
ten  be  sampled. 

2.  All  samples  should  be  passed  through  a  sieve  having  twenty  meshes  per  linear 
inch,  in  order  to  break  up  lumps  and  remove  foreign  material ;  this  is  also  a  very 
effective  method  for  mixing  them  together  in  order  to  obtain  an  average.   For  deter- 
mining the  characteristics  of  a  shipment  of  cement,  the  individual  samples  may  be 
mixed  and  the  average  tested ;  where  time  will  permit,  however,  it  is  recommended 
that  they  be  tested  separately. 

3.  Method  of  Sampling.     Cement  in  barrels  should  be  sampled  through  a  hole 
made  in  the  centre  of  one  of  the  staves,  midway  between  the  heads,  or  in  the  head, 
by  means  of  an  auger  or  a  sampling  iron  similar  to  that  used  by  sugar  inspectors. 
If  in  bags,  it  should  be  taken  from  surface  to  centre. 

CHEMICAL   ANALYSIS 

4.  Method.     As  a  method  to  be  followed  for  the  analysis  of  cement,  that  pro- 
posed by  the  Committee  on  Uniformity  in  the  Analysis  of  Materials  for  the  Port- 


34 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


land  Cement  Industry,  of  the  New  York  Section  of  the  Society  for  Chemical  Indus- 
try, and  published  in  the  Journal  of  the  Society  for  January  15,  1902,  is  recom- 
mended. 

SPECIFIC   GRAVITY 

5.  Apparatus  and  Method.  The  determination  of  specific  gravity  is  most  con- 
veniently made  with  Le  Chatelier's  apparatus.  This  consists  of  a  flask  (D,  Fig.  1) 
of  120  cu.  cm.  (7.32  cu.  ins.)  capacity,  the  neck  of  which  is  about  20  cm.  (7.87  ins.) 

long;  in  the  middle  of  this  neck  is  a 
bulb  (C),  above  and  below  which  are 
two  marks,  F  and  E;  the  volume 
between  these  marks  is  20  cu.  cm. 
(1.22  cu.  ins.).  The  neck  has  a  dia- 
meter of  about  9  mm.  (0.35  in.),  and 
is  graduated  into  tenths  of  cubic  cen- 
timeters above  the  mark  F. 

6.  Benzine  (62°  Baume),  naphtha,  or 
kerosene   free    from  water,  should    be 
used  in  making  the  determination. 

7.  The  specific  gravity  can  be  deter- 
mined in  two  ways :  — 

(1)  The  flask  is  filled  with  either  of 
these  liquids  to  the  lower  mark  (E), 
and  64  gr.  (2.25  oz.)  of   powder,  pre- 
Fio.  1.  —  LE  CHATELIER'S  SPECIFIC  GRAVITY  APPARATUS    viouslv  dried   at   100°  C.  (212°  F.)  and 

cooled  to  the  temperature  of  the  liquid,  is  gradually  introduced  through  the 
funnel  (B)  [the  stem  of  which  extends  into  the  flask  to  the  top  of  the  bulb  (C)], 
until  the  upper  mark  (F)  is  reached.  The  difference  in  weight  between  the  cement 
remaining  and  the  original  quantity  (64  gr.)  is  the  weight  which  has  displaced 
20  cu.  cm. 

8.  (2)  The  whole  quantity  of  the  powder  is  introduced,  and  the  level  of  the  liquid 
rises  to  some  division  of  the  graduated  neck.   This  reading  plus  20  cu.  cm.  is  the 
volume  displaced  by  64  gr.  of  the  powder. 

9.  The  specific  gravity  is  then  obtained  from  the  formula :  — 

-n    r*       -L       Weight  of  Cement 
Specific  Gravity  =  —  — . 

Displaced  Volume 

10.  The  flask,  during  the  operation,  is  kept  immersed  in  water  in  a  jar  (A),  in 
order  to  avoid  variations  in  the  temperature  of  the  liquid.  The  results  should  agree 
within  0.01. 

11.  A  convenient  method  for  cleaning  the  apparatus  is  as  follows:  The  flask  is 
inverted  over  a  large  vessel,  preferably  a  glass  jar,  and  shaken  vertically  until  the 
liquid  starts  to  flow  freely;  it  is  then  held  still  in  a  vertical  position  until  empty; 
the  remaining  traces  of  cement  can  be  removed  in  a  similar  manner  by  pouring  into 
the  flask  a  small  quantity  of  clean  liquid  and  repeating  the  operation. 


REINFORCED  CONCRETE  SPECIFICATIONS 


35 


FINENESS 

12.  Apparatus.     The    sieves   should   be  circular,  about  20  cm.  (7.87  ins.)  in 
diameter,  6  cm.  (2.36  ins.)  high,  and  provided  with  a  pan  5  cm.  (1.97  ins.)  deep, 
and  a  cover. 

13.  The  wire  cloth  should  be  woven  (not  twilled)  from  brass  wire  having  the 
following  diameters: 

No.  100,  0.0045  in.;  No.  200,  0.0024  in. 

14.  This  cloth  should  be  mounted  on  the  frames  without  distortion;  the  mesh 
should  be  regular  in  spacing  and  be  within  the  following  limits :  — 

No.  100,  96  to  100  meshes  to  the  linear  inch. 
No.  200,  188  to  200      " 

15.  Fifty  grams  (1.76  oz.)  or  100  gr.  (3.52  oz.)  should  be  used  for  the  test,  and 
dried  at  a  temperature  of  100°  C.  (212°  F.)  prior  to  sieving. 

16.  Method.     The  thoroughly  dried   and  coarsely  screened  sample  is  weighed 
and  placed  on  the  No.  200  sieve,  which,  with  pan  and  cover  attached,  is  held  in 
one  hand  in  a  slightly  inclined  position,  and  moved  forward  and  backward,  at  the 
same  time  striking  the  side  gently  with  the  palm  of  the  other  hand,  at  the  rate  of 
about  200  strokes  per  minute.    The  operation  is  continued  until  not  more  than 
one  tenth  of  1  per  cent,  passes  through  after  one  minute  of  continuous  sieving.  The 
residue  is  weighed,  then  placed  on  the  No.  100  sieve  and  the  operation  repeated. 
The  work  may  be  expedited  by  placing  in  the  sieve  a  small  quantity  of  large  shot. 
The  results  should  be  reported  to  the  nearest  tenth  of  1  per  cent. 

i 

NORMAL   CONSISTENCY 

17.  Method.     This  can  best  be  determined  by  means  of  Vicat  Needle  Appa- 
ratus, which  consists  of  a  frame  (K),  Fig.  2,  bearing  a  movable  rod  (L),  with  the 
cap  (A)  at  one  end,  and  at  the  other 

the  cylinder  (J5),  1  cm.  (0.39  in.)  in 
diameter,  the  cap,  rod  and  cylinder 
weighing  300  gr.  (10.58  oz.).  The  rod, 
which  can  be  held  in  any  desired 
position  by  a  screw  (F),  carries  an 
indicator,  which  moves  over  a  scale 
(graduated  to  centimeters)  attached 
to  the  frame  (K).  The  paste  is  held 
by  a  conical,  hard-rubber  ring  (7), 
7  cm.  (2.76  ins.)  in  diameter  at  the 
base,  4  cm.  (1.57  ins.)  high,  resting 
on  a  glass  plate  (J)  about  10  cm. 
(3.94  ins.)  square. 

18.  In  making  the  determination,  FIG.  2.  —  VICAT  NEEDLE 

the  same  quantity  of  cement  as  will  be  subsequently  used  for  each  batch  in  making 
the  briquettes  (but  not  less  than  500  grams)  is  kneaded  into  a  paste,  as  described 


36 


PRACTICAL  REINFORCED  CONCRETE  STANDARDS 


in  paragraph  39,  and  quickly  formed  into  a  ball  with  the  hands,  completing  the 
operation  by  tossing  it  six  times  from  one  hand  to  the  other,  maintained  6  ins. 
apart ;  the  ball  is  then  pressed  into  the  rubber  ring,  through  the  larger  opening, 
smoothed  off,  and  placed  (on  its  large  end)  on  a  glass  plate  and  the  smaller  end 
smoothed  off  with  a  trowel ;  the  paste,  confined  in  the  ring,  resting  on  the  plate,  is 
placed  under  the  rod  bearing  the  cylinder,  which  is  brought  in  contact  with  the 
surface  and  quickly  released. 

19.  The  paste  is  of  normal  consistency  when  the  cylinder  penetrates  to  a  point 
in  the  mass  10  mm.  (0.39  in.)  below  the  top  of  the  ring.    Great  care  must  be  taken 
to  fill  the  ring  exactly  to  the  top. 

20.  The   trial  pastes   are  made  with  varying  percentages  of  water   until   the 
correct  consistency  is  obtained. 

PERCENTAGE   OF  WATER   FOR  STANDARD   MIXTURES  l 


Neat 

1-1 

1-2 

1-3 

1-4 

1-5 

Neat 

1-1 

1-2 

1-3 

1-4 

1-5 

18 

12.0 

10.0 

9.0 

8.4 

8.0 

33 

17.0 

13.3 

11.5 

10.4 

9.6 

19 

12.3 

10.2 

9.2 

8.5 

8.1 

34 

17.3 

13.6 

11.7 

10.5 

9.7 

20 

12.7 

10.4 

9.3 

8.7 

8.2 

35 

17.7 

13.8 

11.8 

10.7 

9.9 

21 

13.0 

10.7 

9.5 

8.8 

8.3 

36 

18.0 

14.0 

12.0 

10.8 

10.0 

22 

13.3 

10.9 

9.7 

8.9 

8.4 

37 

18.3 

14.2 

12.2 

10.9 

10.1 

23 

13.7 

11.1 

9.8 

9.1 

8.5 

38 

18.7 

14.4 

12.3 

11.1 

10.2 

24 

14.0 

11.3 

10.0 

9.2 

8.6 

39 

19.0 

14.7 

12.5 

11.2 

10.3 

25 

14.3 

11.6 

10.2 

9.3 

8.8 

40 

19.3 

14.9 

12.7 

11.3 

10.4 

26 

14.7 

11.8 

10.3 

9.5 

8.9 

41 

19.7 

15.1 

12.8 

11.5 

10.5 

27 

15.0 

12.0 

10.5 

9.6 

9.0 

42 

20.0 

15.3 

13.0 

11.6 

10.6 

28 

15.3 

12.2 

10.7 

9.7 

9.1 

43 

20.3 

15.6 

13.2 

11.7 

10.7 

29 

15.7 

12.5 

10.8 

9.9 

9.2 

44 

20.7 

15.8 

13.3 

11.9 

10.8 

30 

16.0 

12.7 

11.0 

10.0 

9.3 

45 

21.0 

16.0 

13.5 

12.0 

11.0 

31 

16.3 

12.9 

11.2 

10.1 

9.4 

46 

21.3 

16.1 

13.7 

12.1 

11.1 

32 

16.7 

13.1 

11.3 

10.3 

9.5 

1  to  1         1  to  2 

1  to  3 

1  to  4 

1  to  5 

Cement  .... 

500         333 

250 

200 

167 

Sand 

500         666 

750 

800 

833 

TIME   OF   SETTING 

21.  Method.     For    this    purpose  the  Vicat  Needle,  which  has  already  been 
described  in  paragraph  17,  should  be  used. 

22.  In  making  the  test,  a  paste  of  normal  consistency  is  molded  and  placed  under 
the  rod  (L),  Fig.  2,  as  described  in  paragraph  18;  this  rod,  bearing  the  cap  (D) 
at  one  end  and  the  needle  (H),  I  mm.  (0.039  in.)  in  diameter  at  the  other,  weighing 

1  The  committee  on  Standard  Specifications  inserts  this  table  for  temporary  use,  to  be  replaced  by  one  to  be 
devised  by  the  Committee  of  the  American  Society  of  Civil  Engineers. 


REINFORCED  CONCRETE  SPECIFICATIONS 


37 


300  gr.  (10.58  oz.).  The  needle  is  then  carefully  brought  in  contact  with  the  surface 
of  the  paste  and  quickly  released. 

23.  The  setting  is  said  to  have  commenced  when  the  needle  ceases  to  pass  a 
point  5  mm.  (0.20  in.)  above  the  upper  surface  of  the  glass  plate,  and  is  said  to  have 
terminated  the  moment  the  needle  does  not  sink  visibly  into  the  mass. 

24.  The  test  pieces  should  be  stored  in  moist  air  during  the  test ;  this  is  accom- 
plished by  placing  them  on  a  rack  over  water  contained  in  a  pan  and  covered  with 
a  damp  cloth,  the  cloth  to  be  kept  away  from  them  by  means  of  a  wire  screen ;  or 
they  may  be  stored  in  a  moist  box  or  closet. 

25.  Care  should  be  taken  to  keep  the  needle  clean,  as  the  collection  of  cement 
on  the  sides  of  the  needle  retards  the  penetration,  while  cement  on  the  point  reduces 
the  area  and  tends  to  increase  the  penetration. 

26.  The  determination  of  the  time  of  setting  is  only  approximate,  being  mate- 
rially affected  by  the  temperature  of  the  mixing  water,  the  temperature  and  hu- 
midity of  the  air  during  the  test,  the  percentage  of  water  used,  and  the  amount  of 
molding  the  paste  receives. 

STANDARD  SAND 

27.  For  the  present,  the  Committee  recommends  the  natural  sand  from  Ottawa, 
111.,  screened  to  pass  a  sieve  having  20  meshes  per  linear  inch  and  retained  on  a 
sieve  having  30  meshes  per  linear  inch;  the  wires  to  have  diameters  of  0.0165  and 
0.0112  in.,  respectively,  i.  e.  half  the  ?» 

width   of  the   opening  in  each  case.     U W *i 

Sand  having  passed  the  No.  20  sieve 
shall  be  considered  standard  when 
not  more  than  1  per  cent,  passes  a 
No.  30  sieve  after  one  minute  con- 
tinuous sifting  of  a  500-gram  sam- 
ple. 

28.  The  Sandusky  Portland  Cement 
Company,   of    Sandusky,   Ohio,   has 
agreed  to  undertake  the  preparation 
of  this  sand  and  to  furnish  it  at  a 
price  only  sufficient  to  cover  the  actual 
cost  of  preparation. 


FORM   OF  BRIQUETTE 

29.  While  the  form  of  the  briquette 
recommended  by  a  former  committee 
of  the  Society  is  not  wholly  satisfac- 
tory, this  committee  is  not  prepared 
to  suggest  any  change,  other  than 
rounding  off  the  corners  by  curves  of 
J-in.  radius,  Fig.  8. 


(<- 


Fia.  3.  —  DETAILS  FOR  BRIQUETTE 


38  PRACTICAL  REINFORCED  CONCRETE  STANDARDS 

MOLDS 

30.  The  molds  should  be  made  of  brass,  bronze,  or  some  equally  non-corrodible 
material,  having  sufficient  metal  in  the  sides  to  prevent  spreading  during  molding. 

31 .  Gang  molds,  which  permit  mold- 
ing a  number  of  briquettes  at  one  time, 
are  preferred  by  many  to  single  molds ; 
since  the  greater  quantity  of  mortar 
FIG.  4.  — DETAILS  FOR  GANG  FLANK  that  can  be  mixed  tends  to  produce 

greater  uniformity  in  the  results.    The  type  shown  in  Fig.  4  is  recommended. 

32.  The  molds  should  be  wiped  with  an  oily  cloth  before  using. 

MIXING 

33.  All  proportions  should  be  stated  by  weight ;  the  quantity  of  water  to  be  used 
should  be  stated  as  a  percentage  of  the  dry  material. 

34.  The  metric  system  is  recommended  because  of  the  convenient  relation  of  the 
gram  and  the  cubic  centimeter. 

35.  The  temperature  of  the  room  and  the  mixing  water  should  be  as  near  21° 
C.  (70°  F.)  as  it  is  practicable  to  maintain  it. 

36.  The  sand  and  cement  should  be  thoroughly  mixed  dry.   The  mixing  should 
be  done  on  some  non-absorbing  surface,  preferably  plate  glass.  If  the  mixing  must 
be  done  on  an  absorbing  surface  it  should  be  thoroughly  dampened  prior  to 
use. 

37.  The  quantity  of  material  to  be  mixed  at  one  time  depends  on  the  number 
of  test  pieces  to  be  made;  about  1000  gr.  (35.28  oz.)  makes  a  convenient  quantity 
to  mix,  especially  by  hand  methods. 

38.  Method.     The  material  is  weighed  and   placed  on  the  mixing  table,  and  a 
crater  formed  in  the  centre,  into  which  the  proper  percentage  of  clean  water  is 
poured ;  the  material  on  the  outer  edge  is  turned  into  the  crater  by  the  aid  of  a  trowel. 
As  soon  as  the  water  has  been  absorbed,  which  should  not  require  more  than  one 
minute,  the  operation  is  completed  by  vigorously  kneading  with  the  hands  for  an 
additional  1^  minutes,  the  process  being  similar  to  that  used  in  kneading  dough. 
A  sand-glass  affords  a  convenient  guide  for  the  time  of  kneading.  During  the  opera- 
tion of  mixing,  the  hands  should  be  protected  by  gloves,  preferably  rubber. 

MOLDING 

39.  Having  worked  the  paste  or  mortar  to  the  proper  consistency,  it  is  at  once 
placed  in  the  molds  by  hand. 

40.  Method.     The  molds  should  be  filled  at  once,  the  material  pressed  in  firmly 
with  the  fingers  and  smoothed  off  with  a  trowel  without  ramming;  the  material 
should  be  heaped  up  on  the  upper  surface  of  the  mold,  and  in  smoothing  off,  the 
trowel  should  be  drawn  over  the  mold  in  such  a  manner  as  to  exert  a  moderate 
pressure  on  the  excess  material.  The  mold  should  be  turned  over  and  the  operation 
repeated. 


REINFORCED  CONCRETE  SPECIFICATIONS 


39 


41.  A  check  upon  the  uniformity  of  the  mixing  and  molding  is  afforded  by  weigh- 
ing the  briquettes  just  prior  to  immersion,  or  upon  removal  from  the  moist  closet. 
Briquettes  which  vary  in  weight  more  than  3  per  cent,  from  the  average  should  not 
be  tested. 


STORAGE   OF  THE   TEST   PIECES 

42.  During  the  first  twenty-four  hours  after  molding,  the  test  pieces  should 
be  kept  in  moist  air  to  prevent  them  from 

drying  out. 

43.  A  moist  closet  or  chamber  is  so  easily 
devised  that  the  use  of  the  damp  cloth  should 
be  abandoned,  if  possible.    Covering  the  test 
pieces  with  a  damp  cloth  is  objectionable,  as 
commonly  used,  because  the  cloth  may  dry 
out  unequally,  and  in  consequence  the  test 
pieces  are  not  all  maintained  under  the  same 
condition.   Where  a  moist  closet  is  not  avail- 
able, a  cloth  may  be  used  and  kept  uniformly 
wet  by  immersing  the  ends  in  water.  It  should 
be  kept  from  direct  contact  with  the  test  pieces 
by  means  of  a  wire  screen  or  some  similar 
arrangement. 

44.  A  moist  closet  consists  of  a  soapstone 
or  slate  box,  or  a  metal-lined  wooden  box  — 
the  metal  lining  being  covered  with  felt  and 
this  felt  kept  wet.    The  bottom  of  the  box  is 
so  constructed  as  to  hold  water,  and  the  sides 
are  provided    with  cleats  for  holding  glass 
shelves  on  which  to  place  the  briquettes.   Care 
should  be  taken  to  keep  the  air  in  the  closet 
uniformly  moist. 

45.  After  twenty-four  hours  in  moist  air,  the 
test  pieces  for  longer  periods  of  time  should  be 
immersed  in  water  maintained  as  near  21°  C. 
(70°  F.)  as  practicable ;  they  may  be  stored  in 
tanks  or  pans,  which  should  be  of  non-cor- 
rodible  material. 


Fio.  5.  —  FORM  OF  CLIP 


TENSILE   STRENGTH 


46.  The  tests  may  be  made  on  any  standard  machine.  A  solid  metal  clip,  as 
shown  in  Fig.  5,  is  recommended.  This  clip  is  to  be  used  without  cushioning  at 
the  points  of  contact  with  the  test  specimen.  The  bearing  at  each  point  of  contact 
should  be  J  in.  wide,  and  the  distance  between  the  centre  of  contact  on  the  same 
clip  should  be  1J  in. 


40  PRACTICAL  REINFORCED  CONCRETE  STANDARDS 

47.  Test  pieces  should  be  broken  as  soon  as  they  are  removed  from  the  water. 
Care  should  be  observed  in  centring  the  briquettes  in  the  testing  machine,  as  cross- 
strains,  produced  by  improper  centring,  tend  to  lower  the  breaking  strength.   The 
load  should  not  be  applied  too  suddenly,  as  it  may  produce  vibration,  the  shock 
from  which  often  breaks  the  briquette  before  the  ultimate  strength  is  reached.  Care 
must  be  taken  that  the  clips  and  the  sides  of  the  briquette  be  clean  and  free  from 
grains  of  sand  or  dirt,  which  would  prevent  a  good  bearing.   The  load  should  be 
applied  at  the  rate  of  600  Ibs.  per  minute.   The  average  of  the  briquettes  of  each 
sample  tested  should  be  taken  as  the  test,  excluding  any  results  which  are  mani- 
festly faulty. 

CONSTANCY   OF  VOLUME 

48.  Methods.     Tests  for  constancy  of   volume    are  divided  into  two  classes: 
(1)  normal  tests,  or  those  made  in  either  air  or  water  maintained  at  about  21°  C. 
(70°  F.),  and  (2)  accelerated  tests,  or  those  made  in  air,  steam,  or  water  at  a  tem- 
perature of  45°  C.  (115°  F.)  and  upward.    The  test  pieces  should  be  allowed  to 
remain  twenty-four  hours  in  moist  air  before  immersion  in  water  or  steam,  or 
preservation  in  air. 

49.  For  these  tests,  pats  about  7J  cm.  (2.95  ins.)  in  diameter,  1J  cm.  (0.49  ins.) 
thick  at  the  centre,  and  tapering  to  a  thin  edge,  should  be  made,  upon  a  clean  glass 
plate  [about  10  cm.  (3.94  ins.)  square],  from  cement  paste  of  normal  consistency. 

50.  Normal  Test.     A  pat  is  immersed  in  water  maintained  as  near  21  C.  (70° 
F.)  as  possible  for  twenty-eight  days,  and  observed  at  intervals.  A  similar  pat  is 
maintained  in  air  at  ordinary  temperature  and  observed  at  intervals. 

51.  Accelerated  Test.     A  pat  is  exposed  in  any  convenient  way  in  an  atmosphere 
of  steam,  above  boiling  water,  in  a  loosely-closed  vessel. 

52.  To  pass  these  tests  satisfactorily,  the  pats  should  remain  firm  and  hard,  and 
show  no  signs  of  cracking,  distortion,  or  disintegration. 

53.  Should  the  pat  leave  the  plate,  distortion  may  be  detected  best  with  a  straight- 
edge applied  to  the  surface  which  was  in  contact  with  the  plate. 


CHAPTER  V 

FOUNDATIONS 

LOADING 

THE  floor  slabs,  beams,  and  girders  throughout  a  building  should  be  designed 
for  full  dead  and  live  load. 

It  is  considered  safe  by  many  architects  and  engineers  to  make  reductions  from 
column  loading  from  floor  to  floor,  on  the  assumption  that  the  entire  space  of  any 
one  floor  will  not  be  loaded  to  its  full  capacity.  The  recommendation  for  floor 
loads  by  a  committee  of  Boston  engineers  acting  as  a  commission  on  the  revision 
of  the  building  laws  is  as  follows :  "  All  new  or  renewed  floors  shall  be  so  con- 
structed as  to  carry  safely  the  weight  to  which  the  proposed  use  of  the  building 
will  subject  them,  and  every  permit  granted  shall  state  for  what  purpose  the  build- 
ing is  designed  to  be  used ;  but  the  least  capacity  per  superficial  square  foot,  exclu- 
sive of  materials  shall  be :  — 

"  For  floors  of  houses  for  habitation,  fifty  pounds. 

"  For  office  floors  and  for  public  rooms  of  hotels  and  houses  exceeding  five  hun- 
dred square  feet,  one  hundred  pounds. 

"  For  floors  of  retail  stores  and  public  buildings,  except  schoolhouses,  one  hun- 
dred and  twenty-five  pounds. 

"  For  floors  of  schoolhouses,  other  than  floors  of  assembly  rooms,  eighty  pounds, 
and  for  floors  of  assembly  rooms,  one  hundred  and  twenty-five  pounds. 

"  For  floors  of  drill  rooms,  dance  halls,  and  riding  schools,  two  hundred  pounds. 

*  The  floors  of  warehouses  and  mercantile  buildings,  at  least  two  hundred  and 
fifty  pounds. 

*  The  loads  for  floors  not  included  in  this  classification  or  for  galleries  shall  be 
determined  by  the  commissioner. 

'  The  full  floor  load  specified  in  this  section  shall  be  included  in  proportioning 
all  parts  of  buildings  designed  for  warehouses,  or  for  heavy  mercantile  and  manu- 
facturing purposes.  In  other  buildings,  however,  certain  reductions  may  be  allowed 
as  follows :  In  girders  carrying  more  than  one  hundred  square  feet  of  floor,  the  live 
load  may  be  reduced  ten  per  cent.  In  columns,  piers,  walls,  and  other  parts  carry- 
ing two  floors,  a  reduction  of  fifteen  per  cent,  of  the  total  live  load  may  be  made ; 
where  three  floors  are  carried  the  total  live  load  may  be  reduced  by  twenty  per 
cent. ;  four  floors,  twenty-five  per  cent. ;  five  floors,  thirty  per  cent. ;  six  floors,  thirty- 
five  per  cent. ;  seven  floors,  forty  per  cent. ;  eight  floors,  forty-five  per  cent. ;  nine  or 
more  floors,  fifty  per  cent. 

*  The  platforms,  landings,  and  stairways  of  every  fire  escape  shall  be  strong 
enough  to  carry  a  load  of  seventy  pounds  to  the  square  foot  in  addition  to  the  weight 
of  material." 


42  PRACTICAL  REINFORCED   CONCRETE  STANDARDS 

The  foundations  should  be  so  designed  as  to  carry  the  load  transmitted  to  them 
by  the  columns,  with  an  equal  loading  per  square  foot  of  bearing  area  for  both  in- 
terior and  exterior  footings,  in  order  to  prevent  cracks  that  might  be  occasioned 
by  any  unequal  settlements. 

CLASSES   OF   FOUNDATIONS 

Foundations  are  usually  supported  in  two  ways,  either  directly  upon  the  soil  or 
upon  piles. 

Borings  or  test  pits  should  be  made  for  every  job  of  any  importance,  to  determine 
the  character  of  the  soil,  as  there  often  may  be  strata  of  soft  material  underlying 
a  hard  surface  material. 

Pile  foundations  should  be  used  wherever  there  is  any  question  as  to  the  bearing 
value  of  the  soil  being  inadequate  to  the  load. 

The  foundation  of  any  structure  is  the  last  place  to  apply  economy. 

The  cost  of  pile  foundations  will  not  average  four  per  cent,  of  the  cost  of  any 
ordinary  building,  and  it  would  seem  unwise  to  jeopardize  ninety-six  per  cent,  to 
save  four  per  cent. 

FOUNDATIONS  DIRECTLY  UPON  THE  SOIL.  These  are  divided  into  two  classes, 
plain  foundations  and  grillage  foundations. 

The  plain  foundations  do  not  generally  require  any  great  amount  of  engineering. 
The  area  of  the  footing  should  be  such  as  to  conform  to  the  bearing  value  of  the 

soil,  which  should  be  predetermined,  and  the  depth 
should  be  at  least  one  and  one  half  times  the  projec- 
tion from  side  of  bearing  area  above,  or  b  =  —  (see  cut) . 


t 
b 

I 


t 

b 

I 


Footings  may  be  built  up  in  successive  steps  or  in 
the  shape  of  a  truncated  pyramid.  The  first  method 
is  the  more  economical  owing  to  the  simplicity  of 
forms.  It  is  difficult  to  keep  the  forms  in  position 
for  the  second  method,  as  a  mass  of  wet  concrete 


deposited  in  them  is  liable  to  float  them. 

The  concrete  in  the  lower  part  of  the  footing  should  not  be  weaker  than  1-3-6, 
and  the  upper  portion  must  be  of  the  same  mixture  as  a  supported  concrete  column. 
Where  an  iron  bearing  plate  is  used  under  a  cast  iron  or  steel  column,  its  area  must 
be  such  that  the  safe  working  strength  of  the  concrete  directly  under  it  is  not 
exceeded. 

Whenever  eccentricity  of  loading  occurs,  it  should  be  properly  taken  care  of  in 
the  design  and  the  error  should  be  guarded  against  of  assuming  the  maximum  load 
per  square  foot  over  the  full  bearing  area. 

When  a  great  amount  of  excavation  is  necessary  to  carry  footings  to  a  satisfac- 
tory foundation,  an  economical  method  is  to  excavate  inside  a  steel  shell  driven 
into  the  ground  as  the  excavation  progresses,  —  this  excavation  to  be  enlarged  at 
the  bottom  of  the  shell  to  obtain  the  required  bearing  area.  The  full  size  of  excava- 
tion is  filled  with  concrete  as  soon  as  the  excavation  is  completed. 

FOUNDATIONS  WITH  STEEL  GRILLAGE.     The  advantages  of  this  type  of  founda- 


FOUNDATIONS 


48 


tion  are  in  the  saving  of  excavation,  and  in  many  cases  shoring  and  pumping,  also 
in  obtaining  a  large  bearing  area  on  a  poor  soil.  There  is  a  considerable  saving  in 
labor  and  concrete  materials  with  this  method,  but  this  saving  in  cost  is  usually 
balanced  by  the  cost  of  the  steel  grillage. 

Grillage  foundations  are  especially  adapted  for  chimneys,  where  it  is  desirous 
to  obtain  a  uniform  distribution  of  stress  over  a  large  area. 

Mr.  E.  L.  Ransome  has  published  formulae  for  this  type  of  foundation  which 
have  been  extensively  used  and  are  reprinted  with  his  permission. 

WALL   AND    PIER    FOOTINGS 

Figures  1  and  2  illustrate  the  general  form  and  arrangement  of  tension  bars  in 
our  standard  wall  and  pier  footings. 


FORMULA    FOR   WALL   FOOTINGS 

We  have  given  in  all  cases  the  width  of  the  wall  (W),  the  load  per  linear  foot  (L), 
and  the  width  of  the  footing  (Wi).  The  total  stress  in  the  tension  bars  or  the  total 
compression  in  the  concrete  per  linear 
foot  is 

^ 

b tress  = 

ID 


SECTION   THROUGH  WALL  FOOTING 


in  which  L  equals  the  total  load  in 
tons,  P  equals  the  projection  in  inches, 
and  D  equals  the  distance  in  inches 
from  the  top  of  the  footing  to  the 
centre  of  the  bars. 

We  have  two  unknown  quantities, 
Stress  and  D.  It  is  therefore  unneces- 
sary to  impose  another  condition,  and 
it  is  that  when  the  safe  compressive 
strength  of  the  concrete  equals  35 
tons  per  square  foot  there  shall  be  16 
square  inches  of  concrete  in  the  area 
above  the  bars  for  each  ton  stress 
or  16  x  Stress  .=  12  x  D,  from  which 
Stress- 1  D. 

This  condition  is  necessary  in  order  that  the  concrete  shall  not  be  strained  be- 
yond its  safe  compressive  strength,  and  should  be  modified  to  suit  this  strength  when 
the  latter  does  not  conform  to  the  value  of  35  tons.  Substituting  this  value  of  Stress 

8  LP 
in  the  above  formula  and  reducing,  we  have  D  equals  the  square  root  of 

21 

Having  obtained  D  from  this  formula,  the  total  stress  in  the  bars  in  tons  =f  D. 
The  bars  may  be  placed  as  shown  on  plan.  The  size  of  the  bars  should  be  so  taken 
that  the  bars  will  not  be  spaced  more  than  12  inches  apart.  The  total  height  (H)  of 
the  footing  should  be  at  least  3  inches  greater  than  the  depth  (D). 


PLAN   OF  WALL  FOOTING 
FlG.  1 


44  PRACTICAL  REINFORCED  CONCRETE  STANDARDS 

Example:  Let  W  =2  feet.   Load  =20  tons  per  lin.  ft.  and  Safe  Bearing  Power  of 
Soil  =2   tons.    Then  FFi=10  feet  and  P=4  feet.    D  equals   the  square  root   of 

8  X  20  X  48  in.  .     ,          .     ,  c 

=  19  inches.   And  Stress  =  j  x  19  =  14.25  tons,  requiring  f -inch  square 

21  p 

bars  4j  inches  on  centres.    Their  length  would  be  W\ =8  feet. 


II.    FORMULA   FOR   PIER   FOOTINGS 

As  in  the  case  for  Wall  footings,  we  have  given  the  dimensions  of  the  supported 
pier  and  footing  (W  and  W*)  and  the  total  load  carried  (L). 

Our  formula  for  obtaining  the  Stress  in  the  .tension  bars  running  in  each  direction 

LxP . 
is in  which  we  have  as  before  the 

3xD 

two  unknown  quantities  Stress  and  D. 
In  order  that  the  concrete  may  not 
be  compressed  beyond  its  safe  work- 
ing strength,  we  impose  the  condition 

4  x  Stress  =  —  X  (W  +  6)    from   which 

2 

G.  Dx(W+6)    c  , 

btress  = -.  Substituting  this 

value  of  Stress  in  the  above  formula 
and  reducing,  we  have  D  equals  the 

square  root  of Having  ob- 

*•  rf-fc     XTTT      .       y»\  O 


ELEVATION   OF  PIER  FOOTING 


tained   D   by  this  formula,  the  total 

Stress  in  tons  equals xD,  from 

8 

which  the  size  and  number  of  bars 
running  in  each  direction  can  be  com- 
puted. These  bars  may  be  made  in 
two  lengths  as  shown  on  plan,  Fig.  2, 
the  shorter  length  being  equal  to  W  +  P. 
The  total  height  (H)  should  not  be  less 
than  D  +  4  inches. 

Example:  Let  W  =  16  inches.  Load 
=  80  tons.  Safe  bearing  power  of  soil 
=  2  tons.  The  required  area  of  base  of 

footing  is  40  square  feet,  and  the  width  (Wi)  equals  the  square  root  of  40  =6  feet 

4  inches  or  76  inches  and  P  =30  inches. 


PLAN  OF  PIER  FOOTING 
FIG.  2 


D  equals  the  square  root  of 

22 


8  x  80  x  30 


=  17  inches.  The  total  stress  would  there- 


fore  be  --X 17  =47  tons  requiring  9  f-inch  bars  or  19  £-inch  bars  in  each  direction. 


FOUNDATIONS  45 

These  bars  should  be  spaced  equally  over  W  D.  The  total  height  (H)  would  be 
D  +  4  inches. 

In  the  examples  given  by  Mr.  Ransome  he  has  used  the  square  twisted  bar,  for 
which  he  has  assumed  a  working  srength  of  20,000  pounds  per  square  inch. 

FOUNDATIONS   ON   PILES 

There  are  two  classes  of  pile  foundations :  — 

First:  where  the  piles  pass  through  a  soft  material  to  a  hard  underlying  strata. 

Second:  Where  the  piles  are  sustained  by  friction  or  suction  and  do  not  reach  a 
point  where  the  penetration  is  suddenly  arrested. 

Wooden  piles  are  more  generally  used,  although  there  are  several  types  of  con- 
crete piles.  As  a  rule,  however,  concrete  piles  cannot  be  used  to  advantage  for  lengths 
of  over  25  or  30  feet,  and  the  economy  in  their  use  consists  in  the  saving  of  the  exca- 
vation for  and  the  placing  of  heavy  concrete  foundations  which  would  be  necessary 
where  wood  piles  must  be  cut  off  at  a  low  grade. 

A  great  many  claims  have  been  made  as  to  the  superior  supporting  value  of  con- 
crete piles  over  wooden  piles.  The  testimony  supporting  these  claims  has  been 
mostly  submitted  by  interested  parties,  and  the  author  recommends  that  a  thorough 
investigation  of  the  character  of  the  soil,  the  design  and  size  of  the  pile,  and  the 
method  of  driving  be  made  before  the  supporting  value  of  the  pile  is  fixed. 

PENETRATION    OF   WOODEN    PILES 

In  the  first  class  of  pile  foundations  the  penetration  due  to  a  2000-pound  hammer 
falling  ten  feet  should  not  be  over  one  inch  for  the  last  blow,  and  if  the  penetration 
does  not  exceed  this  a  safe  load  of  16  tons  per  pile  may  be  assumed.  In  the  second 
class  an  ordinary  rule  is  that  the  penetration  under  the  same  hammer  and  drop  shall 
not  be  over  three  inches  for  the  last  blow,  and  that  a  safe  load  of  10  tons  per  pile 
may  be  assumed. 

There  has  been  considerable  dissension  in  regard  to  this  rule,  inasmuch  that  it 
makes  no  account  of  the  frictional  resistance  of  piles  of  different  sizes. 

W.  M.  Patton  in  his  "  Practical  Treatise  on  Foundations  "  suggests  a  formula 
for  frictional  resistance  of  piles  made  up  as  follows :  — 

S  equals  (W-P)+F  where 

S  =  square  feet  of  surface  of  pile  in  contact  with  soil. 

PF=load  on  pile. 

P  =  bearing  power  of  soil  per  square  foot. 

F  =  working  value  of  friction  of  soil  on  superficial  area  of  pile,  per  square  foot. 

P  is  the  safe  loads  for  various  soils  in  the  following  table,  and  may  be  neglected 
in  loose  soils,  as  its  proportional  value  is  small. 

Ledge  Rock  36  tons  per  square  foot. 

Hard  pan  8      "       " 

Gravel  5      " 

Clean  sharp  sand    4      "       " 
Dry  clay  3      " 


46  PRACTICAL  REINFORCED   CONCRETE   STANDARDS 

Wet  clay  2  tons  per  square  foot. 

Loam        1     "       " 

F  will  vary  from  50  to  150  pounds  per  square  foot  for  soft  semi-fluid  soils,  vary- 
ing with  their  consistency ;  from  150  to  250  pounds  per  square  foot  for  mixed  earths 
and  gritty  soils,  and  from  200  to  300  pounds  per  square  foot  for  compact  clays,  sand, 
and  gravel. 

In  the  eastern  section  of  the  United  States,  spruce  piles  are  the  cheapest.  They 
are  cut  in  lengths  of  from  20  to  50  feet,  and  measure  from  4  to  6  inches  at  the  tip 
and  from  10  to  14  inches  at  the  head. 

For  the  first  class  of  foundations  the  diameter  of  tip  only  should  be  specified,  and 
it  should  not  be  less  than  6  inches  under  the  bark. 

For  the  second  class,  where  friction  is  depended  upon  almost  wholly,  the  size  of 
the  tip  is  of  not  so  much  importance,  and  the  size  of  the  head  should  be  specified 
not  less  than  11  inches. 

It  is  necessary  sometimes  to  use  a  greater  length  of  pile  than  can  be  obtained  in 
spruce.  Hard  pine,  Norway  pine,  or  chestnut  piles  can  be  obtained  in  lengths  up 
to  75  or  80  feet  with  a  head  diameter  of  approximately  16  inches. 

CUTTING    OFF    PILES 

Piles  should  be  cut  off  at  a  grade  where  the  soil  is  constantly  wet,  as  an  alter- 
nately wet  and  dry  condition  will  inevitably  cause  decay. 

Where  piles  are  exposed  to  tide  water  by  filtration  through  the  soil,  it  is  custom- 
ary to  specify  cutting  them  off  at  half  tide  level. 

In  clay  or  muck  which  does  not  permit  the  water  to  escape  readily  on  a  receding 
tide,  the  piles  may  be  cut  off  at  a  foot  or  two  higher  level  without  danger  of  decay. 
Many  cities  and  towns  have  ordinances  requiring  piles  to  be  cut  off  at  certain  fixed 
grades  which  must  be  complied  with. 

SPACING   OF   PILES 

In  hard  soils  piles  may  be  spaced  as  closely  together  as  2  feet  6  inches  on  centres. 
In  soft  soils  they  should  be  spaced  3  feet  or  3  feet  6  inches  on  centres.  Heads  of  piles 
should  be  encased  in  concrete  capping. 

Saw  all  piles  off  in  each  footing  either  at  the  specified  grade  or  lower  if  necessary, 
to  cut  off  any  broomed  or  damaged  heads.  Excavate  around  piles  to  a  depth  of  6 
inches  below  top  of  pile  and  see  that  tops  of  piles  are  clean  and  that  dirt  is  rammed 
solidly  around  them  before  concrete  is  deposited.  The  concrete  should  be  of  suffi- 
ciently rich  mixture  so  that  the  load  carried  on  the  head  of  the  pile  does  not 
exceed  the  safe  compressive  strength  of  the  concrete. 

For  example.  A  pile  with  a  11 -inch  diameter  head  supports  16  tons  or  32,000 
pounds.  The  area  of  the  head  is  approximately  85  square  inches.  32,000  divided  by 
85  equals  376  pounds  per  square  inch.  The  concrete  capping  in  this  case  should  not 
be  leaner  than  1-2J-5. 


OF  THE 

DIVERSITY 

of 


SIMPSON  BROS. 
CORPORATION 

Engineers  and  Contractors 


REINFORCED  CONCRETE.— Foundations, 

Buildings,  Bridges,  Tanks,  etc. 

CONCRETE  MASONRY. 
GRANOLITHIC  Walks,  Driveways,  Steps,  etc. 

ARTIFICIAL  STONE- WORK  of  every  descrip- 
tion. 

NEUCHATEL  or  SEYSSEL  Rock  Asphalt  for 
Basements,  Laundries,  Stables,  Stores,  Brew= 
eries,  Dye-Houses,  Mills,  etc.,  laid  on  wood  or 
cement. 

TAR  CONCRETE  Walks  and  Driveways. 

SANITARY   (Plastic)    Floors  for   Bathrooms, 

Kitchens,  Schools,  Hospitals,  etc. 
HASSAM  (Concrete)  STREET  PAVEMENT. 
Manufacturers  of  SIMBROCO  Concrete  Blocks, 

and  Cast  Stone  for  Buildings  and  Building  Trim. 

166  Devonshire  Street,  Room  58 

BOSTON,   MASSACHUSETTS 

(Only  New  England  Business  Desired) 


"AGRIPPA"  SEPARATOR-CLAMP 

FOR  BEAM  AND  GIRDER  REINFORCEMENT 


SEPARATORS  MADE  IN  ANY  LENGTH  TO 
ACCOMMODATE  ANY  NUMBER  OF  RODS 
c  ITHER  PLAIN  OR  DEFORMED 


Cross  Section 

•Showing 

ACRIPPA 

SEPARATOR  -  CLAMP 


The  necessity  of  keeping  steel  reinforcement  in  the  position  designed  is  recognized 
by  all  engineers  and  architects.  The  cut  above  shows  the  simplest  and  most  econom- 
ical form  that  can  be  devised  for  this  purpose. 

Our  "  Agrippa  "  separator-clamp  admits  using  any  type  of  rod. 

Steel  may  be  bought  in  the  open  market,  and  assembled  on  the  floor  alongside  of 
the  beams. 

When  it  is  placed  in  the  beams,  after  assembling,  the  concrete  may  be  poured  and 
tamped  around  it  without  danger  of  displacement. 

It  is  not  necessary  to  pay  exorbitant  prices  for  the  patented  "  systems  "  of  reinforce- 
ment to  get  this  result. 

"  The  Agrippa  "  separator-clamp  saves  time,  worry  and  money. 

We  have  laid  9000  square  feet  of  floor,  including  girders  and  beams  in  sixteen 
hours  without  a  man  on  steel  reinforcement  after  beginning  concrete  work. 

Provides  means  for  hanging  shafting,  piping,  etc. 

SEPARATOR-CLAMPS  OR  PATENT  RIGHTS  FOR  SALE  BY 

SIMPSON    BROS.    CORPORATION 

166  DEVONSHIRE  ST.  BOSTON,  MASS. 


THE      STANDARD      AMERICAN      BRAND 

Atlas  Portland  Cement 

ALWAYS   UNIFORM 

Productive  Capacity  over 
40,000  Barrels  per  Day 

"Atlas"  Portland  Cement  is  manufactured  from 
the  finest  raw  materials,  under  expert  supervision 
in  every  department  of  the  works,  and  is  specified 
by  leading  engineers  in  the  United  States. 

Write  us  for  publications  on  concrete  construction 

THE   ATLAS   PORTLAND  CEMENT  GO. 

30  Broad  Street,  New  York  City 


Waldo  Brothers 

rC.  S.  WALDO,  Sole  Proprietor) 

102  Milk  Street, 

BOSTON 


New   England    Distributors 

ATLAS  PORTLAND  CEMENT 


JAMES  A.  DAVIS  (&  CO. 

SOLE      N.     E.     AGENTS 

Lehigh  Portland  Cement 

STANDARD  FOR  QUALITY 
"BLANC"  STAINLESS  CEMENT 


'T^HE  Best  White  Cement  in 
-••  the  world.  A  true  Portland, 
and  perfectly  white.  Write  us 
for  particulars  and  prices.  Ex- 
tensively used  in  Government 
buildings  at  Washington,  D.  G. 
for  floors  and  ornamental  work. 

OFFICES  : 

92  State  Street,  Boston 

TELEPHONE    CONNECTIONS    WITH   EVERYWHERE 


REINFORCED   CONCRETE    STABLE,  WITH   ASBESTOS    "  CENTURY "   SHINGLE   ROOF,  BUILT   BY 
SIMPSON   BROS.  CORPORATION   FOR   THEODORE   M.  DAVIS,  NEWPORT,  R.  I. 

Asbestos  "Century"  Shingles 

"The  Roof  that  Outlives  the  Building" 

Asbestos  "  Century  "  Shingles,  the  most  perfect  indestructible  roofing, 
is  made  of  asbestos  fibre  and  hydraulic  cement,  compressed  into  thin 
sheets  under  enormous  hydraulic  pressure.  The  cement  hydrates  and 
crystallizes  around  the  asbestos  fibre,  growing  more  and  more  hard  and 
elastic  with  age.  Asbestos  '*  Century  '"  Shingles  are  fire-proof  and 
climate  proof.  They  do  not  flake  off  or  split  at  the  nail  holes.  Applied 
like  any  shingle  or  slate.  An  Asbestos  "  Century  "  Shingle  roof  will 
outlive  the  building,  without  painting  or  repairs. 

A  great  variety  of  shapes,  in  several  sizes  and  three  colors  —  Newport  Gray 
(light),  Slate  (blue  black),  and  Indian  Red.  Five  cents  per  square  foot  at 
Ambler,  Pennsylvania,  is  the  base  price  without  lap. 


Asbestos 
"Century"  Shingles 


Asbestos 
Building  Lumber 


Reinforced  Asbestos 
Corrugated  Sheathing 


The  Keasbey  &  Mattison  Co. 

FACTORS 

Ambler,  Pennsylvania 


5 


NOTE    CONTINUOUS    BONO 


No  Entire  Collapse  of  any  Arch  Reinforced 
with  CLINTON  WELDED  WIRE  can  occur 

unless  the  weight  imposed  upon  the  arch  is  sufficient  to  strain 
and  break  all  of  the  wires. 

This  is  due  to  the  fact  that  Clinton  Welded  Wire, 

made  from  6  to  10  gauge  drawn  steel  wire,  galvanized  or  plain, 
can  be  laid  in  lengths  up  to  300  feet,  thereby  forming  a  continu- 
ous bond  for  that  distance.  In  a  building  200  feet  long,  for 
instance,  our  reinforcing  is  secured  at  the  front  or  rear  of  the 
building,  and  carried  through  the  entire  distance  without  a  break. 
Heavier  gauge  wire  will  be  laid  in  lengths  up  to  150  feet  and 
locked  or  hooked  to  the  next  sheet,  where  building  requires 
more  than  one  sheet  in  length. 

The  Continuous  Bond  of  Clinton  Electrically  Welded 
Wire  is  the  ONE  best  Reinforcing  for  Concrete 

WIRE  CLOTH  COMPANY 

CLINTON,  MASS. 


FIREPROOFINC  DEPARTMENTS 
ALBERT    OLIVER,  1  Madison  Avenue,  New  YorK 

WASHINGTON -ROSSLYN  SUPPLY  CO.,  Colorado  Bldg.  ST.  LOUIS -HUNKINS-WILLIS  LIME  &  CEMENT  CO. 

CHICAGO  -  CLINTON  WIRE  CLOTH  CO.,  30-32  River  St  SAN  FRANCISCO  -LA.  NORRIS,  835  Monadnock  Bldg. 

SYRACUSE,  N.  Y.  -PARAGON  PLASTER  CO.  SEATTLE-  L.  A.  NORRIS,  909  Alaska  Building 

CLEVELAND -CARL  HORIX,  428  Garfield  Building 


BAY  STATE  BRICK  and 
CEMENT  COATING 


PROTECTS  AND  DECORATES 
CONCRETE,  BRICK  AND  PLASTER  SURFACES 

BAY  STATE  BRICK  and  CEMENT  COATING  is  the  ORIGINAL  COATING  for 
Concrete,  Brick,  and  Plaster  on  both  interior  and  exterior  surfaces.  It  can  be  applied  to 
CONCRETE  and  PLASTER  which  are  not  completely  dried  out  and  ONE  COAT  covers 
better  than  two  coats  of  lead  and  oil  paints  without  the  danger  of  peeling.  It  does  not  dete- 
riorate the  concrete  mixture  as  do  dry  colors  mixed  with  the  cement.  It  makes  a  splendid 
hard  base  for  enamel  work.  It  is  unexcelled  for  use  on  floors,  preventing  dusting.  It  is 
made  in  WHITE  and  COLORS.  It  provides  the  only  way  to  decorate  such  surfaces  with 
UNIFORM  and  harmonious  color.  Made  only  in  LIQUID  FORM,  ready  for  use  (never 
made  in  paste  form).  Booklet  free  giving  specifications,  names  of  specifying  architects 
throughout  the  country  and  cuts  of  nice  houses  where  used. 

Made  only  by 

WADSWORTH,  HOWLAND  $  CO.,  Inc. 

PAINT  AMD   VARXISH  MAKERS 

82  and  84  Washington  Street,  Boston,  Mass. 


A.  W.   HASTINGS 


CO 


BOSTON,  MASS. 

134    to    142    Friend    Street 


DOORS,  FRAMES,  AND  SASH 


Window  Frames  especially  constructed  for  Concrete  Buildings 


BELOW  WE  NAME  A  FEW  BUILDINGS  FURNISHED  BY  US 


Boston  Woven  Hose 
H.  M.  Sawyer  Factory  . 
Simplex  Electric  Co. 
Torrey  &  Co.'s 
Lockport  Block  Co. 
Lumsden  and  Van  Stone 
American  Meter  Co. 


.     Cambridge  3  Bldgs. 

Cambridge 
.     Cambridge 
.      Boston      2  Buildings 
.     East  Boston 

South  Boston 
.     Albany,  N.  Y. 


Bailey  Auto  Co. 

H.  P.  &  E.  Day      . 

Franklin  Yarn  Co. 

Henry  Hubbell       . 

Teele  Mfg.  Co. 

Lydian  Confectionery  Co. 

Stetson  Shoe  Co. 


Springfield 

Seymour,  Conn. 

Franklin 

Bridgeport,  Conn. 

Medford 

Cambridge 

Weymouth 


AND    MANY   OTHERS 


Htoersfoe 


CAMBRIDGE  •  MASSACHUSETTS 
U   •    S   •  A 


YE  01320 


; 
-VU/LX- 


1 74372 


